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| 29 | |
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| 30 | <h2>Update History</h2> |
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| 31 | |
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| 32 | These update notes describe major updates relative to the baseline |
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| 33 | PYTHIA 8.100 version. However, they are less extensive than the |
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| 34 | corresponding update notes for PYTHIA 6. On the other hand, |
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| 35 | whereas the PYTHIA 6 manual is a static document, the PYTHIA 8 |
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| 36 | html/php pages are kept up to date for each subversion. |
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| 37 | |
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| 38 | <br/><br/> |
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| 39 | <b>Important note:</b>version 8.160 does introduce some elements of |
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| 40 | backwards incompatibility. Specifically, "multiple interactions", |
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| 41 | abbreviated MI, haa been renamed "multiparton interactions", MPI. |
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| 42 | This affects many parts of the code and documentation. Also some |
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| 43 | features are deprecated, although remaining until the end of the |
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| 44 | 8.1xx version series. |
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| 45 | |
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| 46 | |
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| 47 | <h3>Main news by version</h3> |
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| 48 | |
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| 49 | <ul> |
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| 50 | |
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| 51 | <li>8.105: 24 February 2008 |
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| 52 | <ul> |
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| 53 | |
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| 54 | <li>New option to initialize with arbitrary beam directions<br/> |
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| 55 | <code>pythia.init( idA, idB, pxA, pyA, pzA, pxB, pyB, pzB)</code></li> |
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| 56 | |
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| 57 | <li>Added capability to set <?php $filepath = $_GET["filepath"]; |
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| 58 | echo "<a href='BeamParameters.php?filepath=".$filepath."' target='page'>";?>beam energy spread |
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| 59 | and beam vertex</a>. |
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| 60 | <br/> |
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| 61 | <b>Warning:</b> as a consequence, the old <code>Beams</code> group of |
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| 62 | settings has been moved to <code>BeamRemnants</code>, and |
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| 63 | <code>Beams</code> is now instead used for machine beam parameters. |
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| 64 | Therefore also some <code>Main</code> settings of this character have been |
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| 65 | regrouped, as follows: |
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| 66 | <table cellspacing="5"> |
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| 67 | <tr> <td>8.100 setting </td> <td>has been moved to </td> </tr> |
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| 68 | <tr> <td><code>Main:idA </code></td> |
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| 69 | <td><code>Beams:idA </code></td> </tr> |
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| 70 | <tr> <td><code>Main:idB </code></td> |
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| 71 | <td><code>Beams:idB </code></td> </tr> |
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| 72 | <tr> <td><code>Main:inCMframe </code></td> |
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| 73 | <td>(<code>Beams:frameType</code>) </td> </tr> |
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| 74 | <tr> <td><code>Main:eCM </code></td> |
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| 75 | <td><code>Beams:eCM </code></td> </tr> |
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| 76 | <tr> <td><code>Main:eA </code></td> |
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| 77 | <td><code>Beams:eA </code></td> </tr> |
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| 78 | <tr> <td><code>Main:eB </code></td> |
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| 79 | <td><code>Beams:eB </code></td> </tr> |
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| 80 | <tr> <td><code>Main:LHEF </code></td> |
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| 81 | <td><code>Beams:LHEF </code></td> </tr> |
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| 82 | </table></li> |
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| 83 | |
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| 84 | <li>The <code>forceHadronLevel()</code> method introduced for standalone |
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| 85 | hadronization.</li> |
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| 86 | |
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| 87 | <li><code>main15.cc</code> illustrated how either full hadronization or |
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| 88 | only decays of some particles can be looped over for the rest of the |
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| 89 | event retained.</li> |
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| 90 | |
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| 91 | <li>The <code>LHAevnt</code> and <code>LHAinit</code> classes have been |
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| 92 | joined into a new <code>LHAup</code> one, with new options that allow |
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| 93 | the writing of a Les Houches Event File.</li> |
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| 94 | |
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| 95 | <li>The <code>SusyLesHouches</code> class updated to handle |
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| 96 | SLHA version 2.</li> |
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| 97 | |
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| 98 | <li>Updated HepMC conversion routine.</li> |
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| 99 | |
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| 100 | <li>The static <code>ErrorMsg</code> class has been removed and |
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| 101 | its functionality moved into the non-static <code>Info</code> class, |
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| 102 | in the renamed Info file.</li> |
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| 103 | |
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| 104 | <li>Further reduction of the use of static, with related code changes. |
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| 105 | This should allow to have several almost independent <code>Pythia</code> |
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| 106 | instances. Some static classes still remain, however, notably for |
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| 107 | random number generation and particle properties.</li> |
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| 108 | |
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| 109 | <li>Limited capability to use two different <code>Pythia</code> instances |
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| 110 | for signal + pileup event generation, see <code>main19.cc</code> for an |
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| 111 | example.</li> |
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| 112 | |
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| 113 | <li>In the <code>Event</code> class the <code>=</code> and |
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| 114 | <code>=+</code> methods have been overloaded to allow the copying |
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| 115 | or appending of event records. Illustrated in <code>main19.cc</code>.</li> |
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| 116 | |
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| 117 | <li>The html and php page formatting improved with |
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| 118 | cascading style sheets.</li> |
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| 119 | |
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| 120 | <li>Several minor improvements and new options, including updated configure |
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| 121 | scripts.</li> |
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| 122 | |
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| 123 | </ul> |
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| 124 | </li> |
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| 125 | |
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| 126 | <li>8.108: 1 May 2008 |
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| 127 | <ul> |
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| 128 | |
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| 129 | <li>Correction in the event record, so that the beam particles in line |
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| 130 | 1 and 2 do not have any mother according to the <code>motherList</code> |
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| 131 | method. Previously the "system" entry in line 0 was counted as their |
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| 132 | mother, which gave rise to an unexpected extra vertex in the conversion |
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| 133 | to the HepMC format.</li> |
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| 134 | |
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| 135 | <li>Support for HepMC version 1 is removed, to simplify the code and |
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| 136 | reflect the evolution of the field.</li> |
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| 137 | |
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| 138 | <li>Status codes are stored in HepMC only as 1 for existing and 2 for |
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| 139 | decayed or fragmented particles (whereas previously the original PYTHIA |
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| 140 | codes were used for the latter).</li> |
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| 141 | |
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| 142 | <li>Parton densities are stored in HepMC as <i>xf(x,Q^2)</i> |
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| 143 | rather than the <i>f(x,Q^2)</i> used in (some) previous versions.</li> |
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| 144 | |
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| 145 | <li>The SusyLesHouches class has ben updated so that reading is fully |
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| 146 | compatible with the SLHA2 standard. </li> |
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| 147 | |
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| 148 | <li>Improved handling of the Higgs width, relevant for massive and thereby |
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| 149 | broad resonance shapes.</li> |
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| 150 | |
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| 151 | <li>The matrix elements for neutralino pair production have now been |
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| 152 | completed and checked.</li> |
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| 153 | |
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| 154 | <li>Ensure that <i>alpha_strong</i> does not blow up, by introducing |
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| 155 | a minimal scale somewhat above <i>Lambda_3</i> (roughly where |
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| 156 | <i>alpha_strong = 10</i>).</li> |
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| 157 | |
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| 158 | <li>New methods <code>isValence1()</code> and <code>isValence2()</code> |
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| 159 | in the <code>Info</code> class.</li> |
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| 160 | |
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| 161 | <li>Protection against division by zero in calculation of decay vertex |
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| 162 | (for zero-mass gluons with zero lifetime, where there should be no |
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| 163 | displacement).</li> |
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| 164 | |
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| 165 | <li>A new compilation option <code>-Wshadow</code> is introduced and |
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| 166 | code is rewritten at all places where this option gave warnings.</li> |
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| 167 | |
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| 168 | <li>Minor library correction to allow compilation with gcc 4.3.0.</li> |
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| 169 | |
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| 170 | </ul> |
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| 171 | </li> |
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| 172 | |
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| 173 | <li>8.114: 22 October 2008 |
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| 174 | <ul> |
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| 175 | |
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| 176 | <li>New rescattering description operational (but still experimental) |
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| 177 | for the case that FSR is not interleaved, but saved until after MPI, |
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| 178 | ISR and beam remnants have been handled. This involves much new code |
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| 179 | in several classes.</li> |
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| 180 | |
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| 181 | <li>A new class <code>PartonSystems</code> is introduced to |
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| 182 | keep track of which partons in the event record belong to which |
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| 183 | subcollision system, plus some further information on each subsystem. |
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| 184 | It takes over functionality previously found as part of the |
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| 185 | <code>Event</code> class, but leaves room for future growth.</li> |
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| 186 | |
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| 187 | <li>Add optional model, wherein an increased <i>pT0</i> turnoff scale |
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| 188 | for MPI and ISR is used for above-average active events, i.e. events that |
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| 189 | already have several MPI's or ISR emissions.</li> |
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| 190 | |
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| 191 | <li>Freeze GRV 94L distribution at small <i>Q^2</i> to avoid blowup.</li> |
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| 192 | |
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| 193 | <li>The <code>pythia.readFile(...)</code> method can now alternatively take |
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| 194 | an <code>istream</code> as argument instead of a <code>filename</code>.</li> |
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| 195 | |
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| 196 | <li>Minor bug correction in <code>PartonLevel.cc</code>; the bug could |
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| 197 | (rarely) give a segmentation fault.</li> |
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| 198 | |
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| 199 | </ul> |
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| 200 | </li> |
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| 201 | |
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| 202 | <li>8.120: 10 March 2009 |
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| 203 | <ul> |
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| 204 | |
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| 205 | <li>New rescattering description further developed, but not yet |
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| 206 | recommended for normal usage.</li> |
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| 207 | |
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| 208 | <li>Include new processes for Large Extra Dimensions and Unparticles, |
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| 209 | contributed by Stefan Ask. New test program <code>main28.cc</code> |
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| 210 | illustrates.</li> |
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| 211 | |
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| 212 | <li>Include further SUSY processes: neutralino-chargino and |
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| 213 | chargino-chargino pairs. The processes should be valid also |
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| 214 | in the case of non-minimal flavour violation and/or CP violation. |
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| 215 | Expanded machinery to keep track of SUSY parameters.</li> |
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| 216 | |
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| 217 | <li>Include backwards evolution of incoming photon as part of the |
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| 218 | <code>SpaceShower</code> initial-state radiation description. This |
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| 219 | allows you to simulate hard collisions where one of the incoming |
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| 220 | partons is a photon. New test program <code>main43.cc</code> |
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| 221 | illustrates.</li> |
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| 222 | |
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| 223 | <li>Allow separate mass and transverse momentum cuts when two hard |
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| 224 | subprocesses are generated in the same event.</li> |
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| 225 | |
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| 226 | <li>The default value for the border between short- and long-lived |
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| 227 | paticles has been changed from 1 mm to 10 mm, to better conform with |
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| 228 | LHC standards, see <?php $filepath = $_GET["filepath"]; |
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| 229 | echo "<a href='ParticleDecays.php?filepath=".$filepath."' target='page'>";?>here</a>. |
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| 230 | The default is still to let all unstable particles decay.</li> |
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| 231 | |
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| 232 | <li>New ISR matrix-element correction to <i>f -> f gamma</i> |
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| 233 | in single <i>W</i> production.</li> |
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| 234 | |
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| 235 | <li>New method <code>Event::statusHepMC</code> returns the status |
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| 236 | code according to the HepMC conventions agreed in February 2009. |
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| 237 | The interface to HepMC now writes out status according to this |
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| 238 | convention.</li> |
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| 239 | |
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| 240 | <li>Add capability to link to FastJet, with expanded configure script |
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| 241 | and Makefile, and with <code>main61.cc</code> as new example.</li> |
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| 242 | |
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| 243 | <li>Update of <code>Makefile.msc</code>, with added support for latest |
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| 244 | Visual C++ Express edition and use of regexp to check nmake version.</li> |
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| 245 | |
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| 246 | <li>Update of <code>LHAFortran.h</code> and |
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| 247 | <code>Pythia6Interface.h</code>, to make the interface to Fortran |
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| 248 | routines work also under Windows. (Thanks to Anton Karneyeu.) |
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| 249 | |
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| 250 | <li>Updated and expanded worksheet.</li> |
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| 251 | |
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| 252 | <li>The manual pages in the <code>xmldoc</code> directory, and thereby |
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| 253 | also those of the <code>htmldoc</code> and <code>phpdoc</code> |
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| 254 | directories, have been significantly updated and expanded. In particular, |
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| 255 | in many places the class of each method is explicitly shown, as well as |
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| 256 | the type of the return value and of the arguments. This upgrade is not |
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| 257 | yet completed, but already covers the more relevant sections. </li> |
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| 258 | |
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| 259 | <li>The unary minus operator in the <code>Vec4()</code> returns a |
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| 260 | reference to a four-vector with all components negated, but leaves |
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| 261 | the original four-vector unchanged. Previously the four-vector itself |
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| 262 | was flipped.</li> |
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| 263 | |
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| 264 | <li>The <code>pPlus()</code> and <code>pMinus()</code> methods of a |
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| 265 | four-vector and an event-record particle are renamed <code>pPos()</code> |
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| 266 | and <code>pNeg()</code>, respectively.</li> |
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| 267 | |
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| 268 | <li>Include a further loop in <code>ProcessLevel</code>, so that a new |
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| 269 | process is generated in case of failures of a less severe nature.</li> |
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| 270 | |
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| 271 | <li>Introduce warning message for unexpected <code>meMode</code> in |
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| 272 | <code>ResonanceWidths</code>.</li> |
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| 273 | |
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| 274 | <li>Les Houches event reading framework has been rearranged for |
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| 275 | more flexibility. Some bugs corrected. Specifically, when scale |
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| 276 | is not set (<code>scale = -1.</code> in the Les Houches standard), |
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| 277 | PYTHIA did not attempt to set this scale itself, which typically |
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| 278 | lead to there not being any ISR or FSR. Now the |
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| 279 | <?php $filepath = $_GET["filepath"]; |
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| 280 | echo "<a href='CouplingsAndScales.php?filepath=".$filepath."' target='page'>";?>rules for normal |
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| 281 | 1-, 2- and 3-body final states</a> are applied, with a trivial |
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| 282 | extension of the 3-body rules for higher multiplicities.</li> |
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| 283 | |
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| 284 | <li>Correct bug in the handling of parton densities, whereby it was |
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| 285 | not possible to switch to a new set, once a first initialization |
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| 286 | had been done.</li> |
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| 287 | |
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| 288 | <li>Correct bugs when several <code>Pythia::init</code> initialization |
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| 289 | calls are made in the same run, specifically in the case that pointers |
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| 290 | to external processes have been handed in. |
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| 291 | |
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| 292 | <li>Changes in <code>main03.cmnd</code> and <code>main04.cmnd</code> |
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| 293 | so that some nonstandard options are commented ou rather than active. |
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| 294 | Related comments inserted also in some other <code>.cmnd</code> files, |
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| 295 | but there without any change in program execution.</li> |
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| 296 | |
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| 297 | <li>A few further minor bug fixes.</li> |
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| 298 | |
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| 299 | <li>Update year to 2009.</li> |
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| 300 | |
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| 301 | </ul> |
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| 302 | </li> |
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| 303 | |
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| 304 | <li>8.125: 16 June 2009 |
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| 305 | <ul> |
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| 306 | |
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| 307 | <li>Hadronization and timlike-shower parameter default values updated |
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| 308 | according to a tune to LEP1 data by Hendrik Hoeth, using the |
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| 309 | Rivet + Professor framework.</li> |
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| 310 | |
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| 311 | <li>Many further SUSY production processes. SLHA readin expanded to cover |
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| 312 | also masses and decay modes. Example <code>main22.cc</code> updated, while |
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| 313 | <code>main33.cc</code> now superfluous and removed. </li> |
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| 314 | |
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| 315 | <li>Also further processes for extra dimensions.</li> |
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| 316 | |
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| 317 | <li>Stefan Ask joins as coauthor.</li> |
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| 318 | |
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| 319 | <li>The <code>TimeShower::shower(...)</code> method has gained |
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| 320 | a new argument, that forces the shower evolution to stop after |
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| 321 | a given number of branchings. A new method |
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| 322 | <code>TimeShower::pTLastInShower()</code> permits the last evolution |
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| 323 | <i>pT</i> to be read out. These extensions can be useful |
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| 324 | for matching studies. |
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| 325 | </li> |
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| 326 | |
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| 327 | <li>New optional argument <code>isInterleaved</code> added to |
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| 328 | <code>TimeShower::branch(...)</code>. Is false by default, but |
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| 329 | true when called from the parton level for interleaved evolution |
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| 330 | of several parton systems, optionally also with ISR and MPI.</li> |
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| 331 | |
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| 332 | <li>New methods <code>UserHooks::canSetResonanceScale()</code> |
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| 333 | and <code>UserHooks:scaleResonance(...)</code> allows an optional |
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| 334 | user choice of the maximum shower scale in resonance decays.</li> |
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| 335 | |
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| 336 | <li>A new method <code>SpaceShower::doRestart()</code> has been |
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| 337 | added, to help distinguish cases when a |
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| 338 | <code>SpaceShower::branch(...)</code> failure forces a complete |
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| 339 | restart of the evolution from ones where only the intended |
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| 340 | current branching has been vetoed. |
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| 341 | |
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| 342 | <li>When multiparton interactions are initialized, it is now |
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| 343 | possible to reduce both <i>pT0</i> and <i>pTmin</i> |
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| 344 | if necessary to find a valid solution where |
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| 345 | <i>sigma_jet > sigma_nondiffractive</i>. Previously |
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| 346 | only the former would be reduced, which could lead to |
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| 347 | infinite loops if too large a <i>pTmin</i> was used. |
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| 348 | Thanks to Sami Kama for pointing out the problem. |
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| 349 | </li> |
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| 350 | |
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| 351 | <li>The rescattering machinery is now essentially completed, and can |
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| 352 | be used also by others than the authors. For now, however, it can only |
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| 353 | be recommended for dedicated studies, not e.g. for generic tunes. |
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| 354 | </li> |
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| 355 | |
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| 356 | <li>Timelike and spacelike showers, and beam remnant handling, |
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| 357 | are modified to handle rescattering partons. Specifically, a new machinery |
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| 358 | is introduced to trace the recoils from the combination of rescattering |
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| 359 | with showers and primordial <i>kT</i>. Can assign space- or timelike |
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| 360 | virtualities to intermediate particles to have energy and momentum |
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| 361 | conserved locally. This affects the <code>PartonLevel</code>, |
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| 362 | <code>MultipartonInteractions</code>, <code>TimeShower</code>, |
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| 363 | <code>SpaceShowe</code>r and <code>BeamRemnants</code> classes. |
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| 364 | Further details to appear in the upcoming article on rescattering. |
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| 365 | (Another change is a reversal to pre-8.114 order for non-interleaved FSR, |
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| 366 | wherein also FSR is treated before beam remnants are attached.) |
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| 367 | </li> |
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| 368 | |
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| 369 | <li>Four new status codes introduced, as part of the rescattering |
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| 370 | description: |
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| 371 | <br/>45 : incoming rescattered parton, with changed kinematics owing |
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| 372 | to ISR in the mother system (cf. status 34); |
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| 373 | <br/>46 : incoming copy of recoiler when this is a rescattered parton |
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| 374 | (cf. status 42); |
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| 375 | <br/>54 : copy of a recoiler, when in the initial state of a different |
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| 376 | system from the radiator; |
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| 377 | <br/>55 : copy of a recoiler, when in the final state of a different |
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| 378 | system from the radiator. |
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| 379 | </li> |
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| 380 | |
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| 381 | <li>New method <code>Info::tooLowPTmin()</code> can tell whether the |
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| 382 | <i>pTmin</i> scales for showers or multiparton interactions are too low. |
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| 383 | </li> |
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| 384 | |
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| 385 | <li>Pion beams allowed, both <i>pi^+</i>, <i>pi^-</i> and |
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| 386 | <i>pi^0</i>. New machinery for the latter, where the valence |
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| 387 | flavour content is chosen to be either <i>d dbar</i> or |
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| 388 | <i>u ubar</i> for each new event. One internal pion PDF |
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| 389 | implemented, with others from LHAPDF.</li> |
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| 390 | |
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| 391 | <li>Treatment of Pomeron-proton collisions begun.</li> |
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| 392 | |
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| 393 | <li>Phase-space handling of hard processes and multiparton interactions |
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| 394 | slightly expanded to better allow for harder PDF's than proton ones, |
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| 395 | e.g. for Pomerons.</li> |
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| 396 | |
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| 397 | <li>The program documentation has been expanded with an |
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| 398 | alphabetical index of all methods that are described on the |
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| 399 | webpages, see the <?php $filepath = $_GET["filepath"]; |
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| 400 | echo "<a href='ProgramMethods.php?filepath=".$filepath."' target='page'>";?>Program Methods</a> |
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| 401 | page. Also other sections of the documentation have been |
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| 402 | updated and expanded, including the worksheet.</li> |
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| 403 | |
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| 404 | <li>Several <code>list</code> methods have been made |
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| 405 | <code>const</code>. For the listing of events two new methods |
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| 406 | have been added, <code>Event::list()</code> and |
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| 407 | <code>Event::list(bool showScaleAndVertex, |
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| 408 | bool showMothersAndDaughters = false)</code>, |
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| 409 | that correspond to special cases of the general method.</li> |
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| 410 | |
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| 411 | <li>A new method <code>Pythia::LHAeventSkip(int nSkip)</code> |
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| 412 | permits a skip-ahead of the reading of external Les Houches |
---|
| 413 | Events, without the necessity to generate the intervening |
---|
| 414 | <code>nSkip</code> events in full. Makes use of the new |
---|
| 415 | <code>LHAup::skipEvent(int nSkip)</code> method to perform |
---|
| 416 | the operations. Mainly intended for debug purposes. |
---|
| 417 | |
---|
| 418 | <li>The <code>ClusterJet</code> jet finder now saves the last |
---|
| 419 | five clustering scales. Also a minor bug fix. Thanks to Nils |
---|
| 420 | Lavesson for this contribution.</li> |
---|
| 421 | |
---|
| 422 | <li>The <code>Particle::m2()</code> method now returns a negative |
---|
| 423 | number when the stored mass <i>m</i> is negative, as used to |
---|
| 424 | indicate spacelike virtualities. Also the |
---|
| 425 | <code>Particle::eCalc()</code>, <code>Particle::mT()</code> and |
---|
| 426 | <code>Particle::mT2()</code> methods have been modified. |
---|
| 427 | </li> |
---|
| 428 | |
---|
| 429 | <li>The <code><<</code> method to print our a four-vector has |
---|
| 430 | been expanded with a fifth number, the invariant length, with a minus |
---|
| 431 | sign for spacelike vectors, and provided within brackets to allow |
---|
| 432 | a simple visual distinction.</li> |
---|
| 433 | |
---|
| 434 | <li>New methods <code>Rndm::dumpState(string fileName)</code> and |
---|
| 435 | <code>Rndm::readState(string fileName)</code> allows to write or |
---|
| 436 | read the state of the random number generator to or from a binary file. |
---|
| 437 | </li> |
---|
| 438 | |
---|
| 439 | <li>New method <code>double GammaReal(double x)</code> returns the |
---|
| 440 | value of the <i>Gamma</i> function for arbitrary real argument. |
---|
| 441 | Some cross sections for extra-dimensional processes rewritten to |
---|
| 442 | make use of it. |
---|
| 443 | </li> |
---|
| 444 | |
---|
| 445 | <li>New example program <code>main29.cc</code> shows how |
---|
| 446 | to set up a fictitious process of a heavy system decaying |
---|
| 447 | to two particles or partons, with decays traced to stable |
---|
| 448 | particles, as relevant for astroparticle applications.</li> |
---|
| 449 | |
---|
| 450 | <li>Main programs that illustrate the HepMC interface have |
---|
| 451 | been updated to use version 2.04, including units and excluding |
---|
| 452 | deprecated output formats.</li> |
---|
| 453 | |
---|
| 454 | <li>The <code>main32.cc</code> example extended also to handle |
---|
| 455 | Les Houches Event Files.</li> |
---|
| 456 | |
---|
| 457 | <li>The Makefile has been modified so that "make clean" only |
---|
| 458 | removes the current compilation and library fles, while |
---|
| 459 | "make distclean" gives a more extensive reset and cleanup. |
---|
| 460 | Thanks to Nils Lavesson for this contribution. Some other |
---|
| 461 | minor Makefile corrections.</li> |
---|
| 462 | |
---|
| 463 | <li>Several main programs that use the |
---|
| 464 | <code>Main:timesToShow</code> mode have been corrected so as |
---|
| 465 | not to crash if this is set to zero. Also some other cosmetics |
---|
| 466 | changes in main programs that do not affect the running.</li> |
---|
| 467 | |
---|
| 468 | <li>Bug correction, in that previously a veto with user hooks |
---|
| 469 | was not propagated from parton showers inside resonance decays. |
---|
| 470 | </li> |
---|
| 471 | |
---|
| 472 | <li>Minor bug fix in <code>TimeShower</code> for kinematics with |
---|
| 473 | unequal beam-particle masses.</li> |
---|
| 474 | |
---|
| 475 | <li>Bug fix so that <code>PartonLevel:MPI = off</code> also works for |
---|
| 476 | minimum-bias events.</li> |
---|
| 477 | |
---|
| 478 | <li>Minor bug fix in the impact-parameter selection of multiparton |
---|
| 479 | interactions. Thanks to Sami Kama for pointing it out.</li> |
---|
| 480 | |
---|
| 481 | <li>String fragmentation for junction topology protected against |
---|
| 482 | numerical instability in boost.</li> |
---|
| 483 | |
---|
| 484 | <li>Bug correction in the handling of particle decays to partons, |
---|
| 485 | where the scale of the partons was set before the partons had been |
---|
| 486 | added to some arrays, leading to indexation out of bounds. |
---|
| 487 | Thanks to Vladislav Burylov for discovering this bug. |
---|
| 488 | </li> |
---|
| 489 | |
---|
| 490 | <li>Bug correction in the handling of particles with inhibited decay, |
---|
| 491 | where the decay vertex would be too far displaced, which could lead to |
---|
| 492 | infinite loop. Thanks to Sami Kama for debugging this. </li> |
---|
| 493 | |
---|
| 494 | <li>Check to avoid infinite loop in matrix-element handling of |
---|
| 495 | two-body decays.</li> |
---|
| 496 | |
---|
| 497 | <li>Bug correction to avoid infinite loops in Dalitz decay treatment. |
---|
| 498 | Some changes in the decay handling logic to allow a new try when the |
---|
| 499 | decay of a particle fails.</li> |
---|
| 500 | |
---|
| 501 | <li>Minor correction, so the pointer to the <code>Info</code> class |
---|
| 502 | is set also for user-written classes derived from <code>LHAup</code>. |
---|
| 503 | </li> |
---|
| 504 | |
---|
| 505 | <li>Correction for typo in the matrix element of the |
---|
| 506 | <code>Sigma3ff2HchgchgfftWW</code> class, for doubly charged Higgs |
---|
| 507 | production. Thanks to Merlin Kole for spotting it.</li> |
---|
| 508 | |
---|
| 509 | <li>Updated colour bookkeeping in junction-antijunction annihilation |
---|
| 510 | avoids later problems in <code>Pythia::check()</code>. </li> |
---|
| 511 | |
---|
| 512 | <li>Minor updates of the <code>Makefile.msc</code> file to work with |
---|
| 513 | Visual Studio 2008. Thanks to David Bailey for these modifications.</li> |
---|
| 514 | |
---|
| 515 | <li>Ensure that <code>nInit</code> in the <code>BeamParticle</code> |
---|
| 516 | class is set also for unresolved lepton beams.</li> |
---|
| 517 | |
---|
| 518 | <li>The <code>VetoEvolution</code> class, derived from |
---|
| 519 | <code>UserHooks</code>, is obsolete and has been removed.</li> |
---|
| 520 | |
---|
| 521 | </ul> |
---|
| 522 | </li> |
---|
| 523 | |
---|
| 524 | <li>8.130: 15 September 2009 |
---|
| 525 | <ul> |
---|
| 526 | |
---|
| 527 | <li>New machinery that allows multiparton interactions inside diffractive |
---|
| 528 | systems. Also new optional Pomeron flux factors and Pomeron PDFs. |
---|
| 529 | New page on <?php $filepath = $_GET["filepath"]; |
---|
| 530 | echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>diffraction</a> added, where |
---|
| 531 | further details are collected. Still not tuned, so to be used with |
---|
| 532 | caution.</li> |
---|
| 533 | |
---|
| 534 | <li>Make Peter Skands' "Tune 1" parameters for ISR and MPI default. |
---|
| 535 | The older simpler tune is still available as an option, see |
---|
| 536 | <code><?php $filepath = $_GET["filepath"]; |
---|
| 537 | echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:pp</a></code>. |
---|
| 538 | </li> |
---|
| 539 | |
---|
| 540 | <li>New possible choices for a second hard process: charmonium, |
---|
| 541 | bottomonium, top pair and single top.</li> |
---|
| 542 | |
---|
| 543 | <li>New code for pair production of generic colour-triplet scalar, |
---|
| 544 | fermion or vector. Largely written by Johan Bijnens, partly recycling |
---|
| 545 | existing code.</li> |
---|
| 546 | |
---|
| 547 | <li>Add user hooks possibility to veto event after a given number |
---|
| 548 | of multiparton interactions.</li> |
---|
| 549 | |
---|
| 550 | <li>Add instructions how PYTHIA 8 can be used from inside ROOT. |
---|
| 551 | Thanks to Andreas Morsch for providing the text and Rene Brun |
---|
| 552 | for a simple example.</li> |
---|
| 553 | |
---|
| 554 | <li>The <code>main21.cc</code> example extended with an option |
---|
| 555 | for a single-particle gun.</li> |
---|
| 556 | |
---|
| 557 | <li>Improvements and bug fixes in rescattering framework.</li> |
---|
| 558 | |
---|
| 559 | <li>New method <code>Hist::table(string fileName)</code> provides a |
---|
| 560 | more direct way to print a two-column table of histogram contents |
---|
| 561 | into a file than the current <code>Hist::table(ostream& os = cout)</code>. |
---|
| 562 | </li> |
---|
| 563 | |
---|
| 564 | <li>Modify reading of external files so that a line only consisting of |
---|
| 565 | control characters counts as empty, the same way as a line only consisting |
---|
| 566 | of blanks already did. This includes carriage return, tabs and a few more, |
---|
| 567 | the ones represented by <code>\n \t \v \b \r \f \a</code>. Applies to |
---|
| 568 | Les Houches Event files, settings files and particle data files. </li> |
---|
| 569 | |
---|
| 570 | <li>Fix it so that the read-in of a Les Houches Event File for the |
---|
| 571 | hardest process can be combined with the faciliy to select a specified |
---|
| 572 | second hard process.</li> |
---|
| 573 | |
---|
| 574 | <li>New empty base class method <code>LHAup::fileFound()</code> |
---|
| 575 | allows the derived class <code>LHAupLHEF</code> to signal more |
---|
| 576 | clearly that a failed initialization is caused by a failure to open |
---|
| 577 | the desired file. </li> |
---|
| 578 | |
---|
| 579 | <li>Check that a pointer to an <code>LHAup</code> object has been set |
---|
| 580 | in <code>Pythia::LHAeventList()</code> and |
---|
| 581 | <code>Pythia::LHAeventSkip(...)</code> calls.</li> |
---|
| 582 | |
---|
| 583 | <li>Updated configure and Makefile, e.g. to build shared libraries |
---|
| 584 | on Mac OS X.</li> |
---|
| 585 | |
---|
| 586 | <li>The options with a direct link to hard-process generation |
---|
| 587 | in PYTHIA 6 has been removed. It is hardly ever used but |
---|
| 588 | complicates the build structure. (Owing to its usefulness for some |
---|
| 589 | debug work, it was reinstated in a limited form in version 8.135. |
---|
| 590 | Thus <code>main51.cc</code> now contains the complete interface, |
---|
| 591 | previously in separate files, and commented-out lines in |
---|
| 592 | <code>examples/Makefile</code> suggest how PYTHIA 6 could be linked.) |
---|
| 593 | </li> |
---|
| 594 | |
---|
| 595 | <li>New argument to <code>Info::errorMsg(...)</code> allows to |
---|
| 596 | show all error messages of a specific kind rather than only the |
---|
| 597 | first one, e.g. for initialization.</li> |
---|
| 598 | |
---|
| 599 | <li>Correction in decay table of righthanded Majorana neutrinos. |
---|
| 600 | Thanks to Arnaud Ferrari and Vladimir Savinov.</li> |
---|
| 601 | |
---|
| 602 | <li>Correction in expressions in the manual for <i>H^+-</i> couplings |
---|
| 603 | to an <i>h^0</i>, <i>H^0</i> or <i>A^0</i> and a <i>W^+-</i>. |
---|
| 604 | Thanks to Rikard Enberg.</li> |
---|
| 605 | |
---|
| 606 | <li>Fix for accessing uninitialized memory, caused by accessing the |
---|
| 607 | daughters of the incoming beams before these daughters actually existed. |
---|
| 608 | Thanks to David Bailey and Sami Kama. |
---|
| 609 | </li> |
---|
| 610 | |
---|
| 611 | <li>Uninitialized photon PDF inside the proton could give crazy results |
---|
| 612 | for processes with incoming photons. Thanks to Adam Davison.</li> |
---|
| 613 | |
---|
| 614 | <li>Bug fix such that finite lifetimes can be set also for particles |
---|
| 615 | produced in the hard process. To exemplify, the bug affected |
---|
| 616 | <i>tau</i> leptons produced in <i>Z^0</i> and <i>W^+-</i> |
---|
| 617 | decays. Thanks to Troels Petersen.</li> |
---|
| 618 | |
---|
| 619 | <li>Bug fix in <code>TimeShower</code>, that <code>beamOffset</code> |
---|
| 620 | could remain uninitialized. Thanks to Sami Kama.</li> |
---|
| 621 | |
---|
| 622 | <li>Minor correction to resonance decays: fail if the allowed mass |
---|
| 623 | range of a Breit-Wigner resonance is a small fraction of the total |
---|
| 624 | area under the resonance curve.</li> |
---|
| 625 | |
---|
| 626 | <li>Correction when all three valence quarks were kicked out from a |
---|
| 627 | proton and could give false messages that beam momentum had been |
---|
| 628 | used up.</li> |
---|
| 629 | |
---|
| 630 | <li>Clarify status codes needed for hadron-level standalone runs in |
---|
| 631 | order to avoid error messages, and modify the <code>main21.cc</code> |
---|
| 632 | example accordingly. </li> |
---|
| 633 | |
---|
| 634 | <li>Minor corrections in the processes for extra dimensions.</li> |
---|
| 635 | |
---|
| 636 | <li>Some other minor additions to existing facilities |
---|
| 637 | and minor bug fixes.</li> |
---|
| 638 | |
---|
| 639 | </ul> |
---|
| 640 | </li> |
---|
| 641 | |
---|
| 642 | <li>8.135: 10 January 2010 |
---|
| 643 | <ul> |
---|
| 644 | |
---|
| 645 | <li>All usage of static member methods inside Pythia8 has now been |
---|
| 646 | eliminated. This simplifies for you to have several simultaneous |
---|
| 647 | <code>Pythia</code> instances that are run with different conditions. |
---|
| 648 | The three main classes affected by this are the <code>Settings</code> |
---|
| 649 | and <code>ParticleData</code> databases and the <code>Rndm</code> |
---|
| 650 | random-number generator. You can no longer address the methods of these |
---|
| 651 | classes directly, but have to address them via the <code>settings</code>, |
---|
| 652 | <code>particleData</code> and <code>rndm</code> instances in the |
---|
| 653 | respective <code>Pythia</code> object. Also some other smaller pieces |
---|
| 654 | of code are affected, e.g. Standard Model and SUSY couplings |
---|
| 655 | (the latter in new files). |
---|
| 656 | <br/><b>Note 1</b>: The documentation has been updated accordingly |
---|
| 657 | on these webpages, but the "A Brief Introduction to PYTHIA 8.1" |
---|
| 658 | still refers to the old behaviour of version 8.100. |
---|
| 659 | <br/><b>Note 2</b>: the interface to the external LHAPDF library remains |
---|
| 660 | static, since LHAPDF is written in Fortran and thus by definition |
---|
| 661 | static. |
---|
| 662 | <br/><b>Note 3:</b> if you want to have momentum smearing in |
---|
| 663 | <code>CellJet</code> you now need to send in a pointer to a |
---|
| 664 | random-number generator. |
---|
| 665 | </li> |
---|
| 666 | |
---|
| 667 | <li>Ten new proton PDF sets are made available internally: |
---|
| 668 | MRST LO* (2007), MRST LO** (2008), MSTW 2008 LO (central member), |
---|
| 669 | MSTW 2008 NLO (central member), CTEQ6L, CTEQ6L1, CTEQ6.6 (NLO, |
---|
| 670 | central member), CT09MC1, CT09MC2, and CT09MCS, see |
---|
| 671 | <?php $filepath = $_GET["filepath"]; |
---|
| 672 | echo "<a href='PDFSelection.php?filepath=".$filepath."' target='page'>";?>PDF Selection</a>. The Pomeron PDF data |
---|
| 673 | files have been renamed for consistency. Thanks to Tomas Kasemets |
---|
| 674 | for help with this [<a href="Bibliography.php" target="page">Kas10</a>]. |
---|
| 675 | </li> |
---|
| 676 | |
---|
| 677 | <li>New parameters <code>TimeShower:pTmaxFudgeMPI</code> and |
---|
| 678 | <code>SpaceShower:pTmaxFudgeMPI</code> introduced, to give the same |
---|
| 679 | functionality for multiparton interactions that |
---|
| 680 | <code>TimeShower:pTmaxFudge</code> and <code>SpaceShower:pTmaxFudge</code> |
---|
| 681 | do for the hardest.</li> |
---|
| 682 | |
---|
| 683 | <li>A few extensions of the <code>UserHooks</code> framework. |
---|
| 684 | New methods <code>UserHooks:canVetoISREmission()</code> and |
---|
| 685 | <code>UserHooks::doVetoISREmission(...)</code> allows the latest |
---|
| 686 | initial-state emission to be studied before being finalized, |
---|
| 687 | with the possibility to veto it. |
---|
| 688 | Similarly <code>Userhooks:canVetoFSREmission()</code> and |
---|
| 689 | <code>UserHooks::doVetoFSREmission(...)</code> can be used to |
---|
| 690 | veto the latest final-state emission.</li> |
---|
| 691 | |
---|
| 692 | <li>A number of loop counters have been introduced in the |
---|
| 693 | <code>Info</code> class, that offers some further information on |
---|
| 694 | the progress of the event generation, for use e.g. in conjunction |
---|
| 695 | with the <code>UserHooks</code> facility.</li> |
---|
| 696 | |
---|
| 697 | <li>The <code>Pythia::initTunes(...)</code> method is made public, so that |
---|
| 698 | it can be called before the normal call from <code>Pythia::init(...)</code>. |
---|
| 699 | That way it is possible to start out from a given tune and change a few |
---|
| 700 | of the parameters. |
---|
| 701 | </li> |
---|
| 702 | |
---|
| 703 | <li>Bug corrected in <code>LHAFortran.h</code> for hard-process input |
---|
| 704 | from Fortran commonblock. This did not work properly when the input |
---|
| 705 | was used in combination with a second hard process generated internally. |
---|
| 706 | Thanks to Mikhail Kirsanov and Roberto Chierici. |
---|
| 707 | |
---|
| 708 | <li>Insertion of missing initialization of <code>isInit</code> in the |
---|
| 709 | <code>Settings</code> and <code>ParticleData</code> constructors, and |
---|
| 710 | <code>nInit</code> for <code>BeamParticle</code>. |
---|
| 711 | Thanks to Leif Lönnblad.</li> |
---|
| 712 | |
---|
| 713 | <li>Updated <code>Makefile.msc</code> for Windows users.</li> |
---|
| 714 | |
---|
| 715 | <li>Fix of some non-optimal use of booleans, that give warnings on |
---|
| 716 | a Windows compiler. Thanks to Anton Karneyeu.</li> |
---|
| 717 | |
---|
| 718 | <li>New options for the <?php $filepath = $_GET["filepath"]; |
---|
| 719 | echo "<a href='SUSYLesHouchesAccord.php?filepath=".$filepath."' target='page'>";?> |
---|
| 720 | SUSY Les Houches Accord</a> such that, by default, |
---|
| 721 | particle and decay data are not overwritten for known Standard Model |
---|
| 722 | particles (including <i>Z^0</i>, <i>W^+-</i> and <i>t</i>, |
---|
| 723 | but excluding the Higgs).</li> |
---|
| 724 | |
---|
| 725 | <li>Bug fix in <code>SusyLesHouches</code>, where the reading of SLHA |
---|
| 726 | information embedded in an LHEF would not stop at the end of the header |
---|
| 727 | section.</li> |
---|
| 728 | |
---|
| 729 | <li>Bug correction for undefined secondary widths where decay products |
---|
| 730 | together are heavier than the mother. Also unit default secondary width |
---|
| 731 | values in the <code>DecayChannel</code> constructor.</li> |
---|
| 732 | |
---|
| 733 | <li>Documentation updated, including change of current year to 2010.</li> |
---|
| 734 | |
---|
| 735 | </ul> |
---|
| 736 | </li> |
---|
| 737 | |
---|
| 738 | <li>8.140: 16 July 2010 |
---|
| 739 | <ul> |
---|
| 740 | |
---|
| 741 | <li>Four new draft <?php $filepath = $_GET["filepath"]; |
---|
| 742 | echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>tunes</a> available.</li> |
---|
| 743 | |
---|
| 744 | <li>Introduction of a new scenario for production of Hidden-Valley |
---|
| 745 | particles, and interleaved showering in the QCD and HV sectors, see |
---|
| 746 | the new <?php $filepath = $_GET["filepath"]; |
---|
| 747 | echo "<a href='HiddenValleyProcesses.php?filepath=".$filepath."' target='page'>";?>Hidden Valleys</a> |
---|
| 748 | description. A longer physics writeup is available [<a href="Bibliography.php" target="page">Car10</a>]. |
---|
| 749 | </li> |
---|
| 750 | |
---|
| 751 | <li>Implementation of <i>2 -> 3</i> phase space selection intended |
---|
| 752 | for QCD processes with massless partons. A new set of matching |
---|
| 753 | <?php $filepath = $_GET["filepath"]; |
---|
| 754 | echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>phase space cut parameters</a>. |
---|
| 755 | The <?php $filepath = $_GET["filepath"]; |
---|
| 756 | echo "<a href='QCDProcesses.php?filepath=".$filepath."' target='page'>";?>ten different QCD <i>2 -> 3</i> |
---|
| 757 | processes</a> have been implemented making use of this new |
---|
| 758 | possibility, so far without a complete handling of possible colour |
---|
| 759 | flows, however.</li> |
---|
| 760 | |
---|
| 761 | <li>New processes have been added for |
---|
| 762 | <?php $filepath = $_GET["filepath"]; |
---|
| 763 | echo "<a href='CompositenessProcesses.php?filepath=".$filepath."' target='page'>";?>contact interactions</a> in |
---|
| 764 | <i>q q -> q q</i> and <i>q qbar -> q qbar</i> scattering.</li> |
---|
| 765 | |
---|
| 766 | <li>A process has been added for TeV^-1 Sized |
---|
| 767 | <?php $filepath = $_GET["filepath"]; |
---|
| 768 | echo "<a href='ExtraDimensionalProcesses.php?filepath=".$filepath."' target='page'>";?>Extra Dimensions</a>, which |
---|
| 769 | involves the electroweak KK gauge bosons, i.e. <i>gamma_{KK}/Z_{KK}</i>, |
---|
| 770 | in one TeV^-1 sized extra dimension; see <code>main30.cc</code> for |
---|
| 771 | an example. This scenario is described in [<a href="Bibliography.php" target="page">Bel10</a>]. Thanks to |
---|
| 772 | Noam Hod and coworkers for contributing this code.</li> |
---|
| 773 | |
---|
| 774 | <li>In the Randall-Sundrum extra-dimensional scenario a new option has |
---|
| 775 | been added where SM fields can exist in the bulk rather than only on |
---|
| 776 | a brane. (Still under development.) Furthermore production of a |
---|
| 777 | Kaluza-Klein gluon state has been added, and the <code> main28.cc</code> |
---|
| 778 | test program extended.</li> |
---|
| 779 | |
---|
| 780 | <li>The scenario for monojets in Large Extra Dimensions has been expanded |
---|
| 781 | with an alternative for scalar graviton exchange instead of tensor one. |
---|
| 782 | </li> |
---|
| 783 | |
---|
| 784 | <li>New parameters for maximum scale of |
---|
| 785 | <?php $filepath = $_GET["filepath"]; |
---|
| 786 | echo "<a href='TimelikeShowers.php?filepath=".$filepath."' target='page'>";?>timelike showers</a>, |
---|
| 787 | <code>TimeShower:pTmaxMatch</code>, and the dampening of hard radiation, |
---|
| 788 | <code>TimeShower:pTdampMatch</code> and <code>TimeShower:pTdampFudge</code>, |
---|
| 789 | by analogy with corresponding ones for spacelike showers. Also new method |
---|
| 790 | <code>TimeShower:limitPTmax(...)</code> to implement alternative procedures. |
---|
| 791 | For dipoles stretched to the beam the new switch |
---|
| 792 | <code>TimeShower:dampenBeamRecoil</code> allows to dampen radiation |
---|
| 793 | close to the beam direction, with a changed default behaviour.</li> |
---|
| 794 | |
---|
| 795 | <li>Azimuthal anisotropies from coherence arguments have been introduced |
---|
| 796 | for the spacelike parton showers, see <code>SpaceShower:phiIntAsym</code> |
---|
| 797 | and <code>SpaceShower:strengthIntAsym</code>. |
---|
| 798 | Also azimuthal anisotropies from gluon polarization have been introduced |
---|
| 799 | for the spacelike parton showers, see <code>SpaceShower:phiPolAsym</code>, |
---|
| 800 | and updated for timelike parton showers, see |
---|
| 801 | <code>TimeShower:phiPolAsym</code>.</li> |
---|
| 802 | |
---|
| 803 | <li>Improvements for the matching to POWHEG LHEF-style input illustrated |
---|
| 804 | by the new <code>main71.cc</code> example. See also [<a href="Bibliography.php" target="page">Cor10</a>].</li> |
---|
| 805 | |
---|
| 806 | <li>A set of new processes <i>gamma gamma -> f fbar</i>, with <i>f</i> |
---|
| 807 | quarks or leptons. Code for equivalent photon flux around an unresolved |
---|
| 808 | proton, with more to come. Thanks to Oystein Alvestad. |
---|
| 809 | </li> |
---|
| 810 | |
---|
| 811 | <li>A new option has been included to dampen the growth of the diffractive |
---|
| 812 | cross sections, see <?php $filepath = $_GET["filepath"]; |
---|
| 813 | echo "<a href='TotalCrossSections.php?filepath=".$filepath."' target='page'>";?>Total Cross |
---|
| 814 | Sections</a>.</li> |
---|
| 815 | |
---|
| 816 | <li>A new method <code>virtual int SigmaProcess::idSChannel()</code> |
---|
| 817 | has been introduced. If overloaded to return a nonzero value then a |
---|
| 818 | <i>2 -> n</i> process will appear listed as a <i>2 -> 1 -> n</i> one. |
---|
| 819 | That is, an intermediate resonance with the requested identity will be |
---|
| 820 | inserted in the event record, even without appearing in the calculation |
---|
| 821 | of the matrix element proper. Thanks to Noam Hod for idea and code.</li> |
---|
| 822 | |
---|
| 823 | <li>A new method <code>SigmaProcess::convertM2()</code> has been introduced |
---|
| 824 | to optionally allow the <code>SigmaProcess::sigmaHat()</code> to return |
---|
| 825 | the squared matrix element rather than <i>d(sigmaHat)/d(tHat)</i> for |
---|
| 826 | <i> 2 -> 2 </i> processes. Furthermore kinematics is stored in the new |
---|
| 827 | <code>mME</code> and <code>pME</code> vectors for alternative cross |
---|
| 828 | section encodings.</li> |
---|
| 829 | |
---|
| 830 | <li>Different encoding of the <i>f fbar -> Z W</i> cross section, |
---|
| 831 | contributed by Merlin Kole, based on the cross section of |
---|
| 832 | Brown, Sahdev and Mikaelian. Gives a distinctly different cross section |
---|
| 833 | than the previous based on EHLQ (including their bug fix). |
---|
| 834 | In particular the problem with negative cross sections is now fixed.</li> |
---|
| 835 | |
---|
| 836 | <li>Minor updates: pass <code>xmlPath</code> to new MSTW and CTEQ PDFs; |
---|
| 837 | reset beams earlier to give cleaner documentation.</li> |
---|
| 838 | |
---|
| 839 | <li>The H1 Fit B LO parametrization to the Pomeron PDF has been included, |
---|
| 840 | and made new default for Pomerons. Thanks to Paul Newman for providing |
---|
| 841 | the data files.</li> |
---|
| 842 | |
---|
| 843 | <li>Three changes, in principle unrelated, but with the common objective |
---|
| 844 | to make the generation of a given event depend only on the values |
---|
| 845 | determined during the initialization stage and on the state of the |
---|
| 846 | random-number generator when the event is begun. The new default |
---|
| 847 | should ensure a reproducible stop-and-restart behaviour, convenient |
---|
| 848 | for debug purposes. Thanks to Michael Schmelling for stressing the |
---|
| 849 | desire for such a behaviour. |
---|
| 850 | <br/>(i) Introduction of a new option <code><?php $filepath = $_GET["filepath"]; |
---|
| 851 | echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?> |
---|
| 852 | PhaseSpace:increaseMaximum</a></code> that allows to switch between |
---|
| 853 | two strategies for handling the (hopefully rare) cases when the |
---|
| 854 | assumed maximum of the cross section function is exceeded during the |
---|
| 855 | event generation, with a changed default behaviour. In the old |
---|
| 856 | default the maximum could be increased if it was exceeded during the run, |
---|
| 857 | thereby introducing a memory of the previously generated events. |
---|
| 858 | <br/>(ii) Updated handling of random numbers with Gaussian distributions. |
---|
| 859 | The <code>gauss()</code> method now only generates one value at a time. |
---|
| 860 | Instead the new <code>gauss2()</code> method returns a pair of Gauss |
---|
| 861 | numbers, with related time savings. In the old approach one Gaussian |
---|
| 862 | number could be buffered, which introduced a memory. |
---|
| 863 | <br/>(iii) Minor bug fix in <code>MiniStringFragmentation</code>, where |
---|
| 864 | the popcorn baryon state was not reset for each new system, again |
---|
| 865 | giving a (flawed) memory.</li> |
---|
| 866 | |
---|
| 867 | <li>New directory <code>rootexample</code> with a simple code example |
---|
| 868 | how to use ROOT for histogramming in PYTHIA runs. See |
---|
| 869 | <?php $filepath = $_GET["filepath"]; |
---|
| 870 | echo "<a href='ROOTusage.php?filepath=".$filepath."' target='page'>";?>ROOT Usage</a> for details. Thanks to Rene Brun. |
---|
| 871 | </li> |
---|
| 872 | |
---|
| 873 | <li>In the <code>HepMCinterface</code> the checks for unhadronized |
---|
| 874 | quarks and gluons are not performed if hadronization has been switched |
---|
| 875 | off.</li> |
---|
| 876 | |
---|
| 877 | <li>The <code>UserHooks::initPtr(...)</code> has been expanded so that |
---|
| 878 | pointers to more classes (beam particles, random number, couplings, etc.) |
---|
| 879 | are sent in, thereby increasing the scope of possible user-written code. |
---|
| 880 | Also, the <code>UserHooks::doVetoProcessLevel(Event& process)</code> |
---|
| 881 | now allows the <code>process</code> event record to be modified, |
---|
| 882 | even if it is not recommended. The new <code>Info::pTnow()</code> |
---|
| 883 | method returns the current <i>pT</i> scale of the combined MPI, ISR |
---|
| 884 | and FSR evolution, which can be useful for some user hooks decisions. |
---|
| 885 | </li> |
---|
| 886 | |
---|
| 887 | <li>Histograms of the <code>Hist</code> class can now be booked |
---|
| 888 | with up to 1000 bins, instead of the previous maximum 100. All bins |
---|
| 889 | can be written to file, but the line-printer style printing will join |
---|
| 890 | nearby bins so at most 100 are printed, as before. </li> |
---|
| 891 | |
---|
| 892 | <li>Updated <code>configure</code> and <code>Makefile</code> |
---|
| 893 | to allow 64-bit compilation and more options. Thanks to Mikhail Kirsanov, |
---|
| 894 | Rene Brun and Fons Rademakers.</li> |
---|
| 895 | |
---|
| 896 | <li>Bug fix in <code>ProcessLevel</code> for colour flow checks of |
---|
| 897 | junctions. Enables the decay of a neutralino to three quarks, e.g. |
---|
| 898 | Thanks to Nils-Erik Bomark.</li> |
---|
| 899 | |
---|
| 900 | <li>Bug fixes in <code>TimeShower</code>, where recoil partners in resonance |
---|
| 901 | decays of coloured particles, and recoil partners in QED dipoles when beams |
---|
| 902 | are not allowed to take a recoil, might not be correctly identified. </li> |
---|
| 903 | |
---|
| 904 | <li>Bug fix in <code>SpaceShower</code>: when used with a fixed |
---|
| 905 | <i>alpha_strong</i>, the threshold enhancement factor of |
---|
| 906 | <i>g -> Q Qbar</i> became undefined. Thanks to Stefan Prestel.</li> |
---|
| 907 | |
---|
| 908 | <li>Bug fix in initialization of resonance widths, where the |
---|
| 909 | <code>minWidth</code> parameter could be used uninitialized, |
---|
| 910 | occasionally resulting in strange initialization problems when |
---|
| 911 | kinematics needs to force at least one resonance to be off-shell.</li> |
---|
| 912 | |
---|
| 913 | <li>Minor updates of <code>main06.cc</code>, <code>main10.cc</code> |
---|
| 914 | and <code>main23.cc</code>.</li> |
---|
| 915 | |
---|
| 916 | <li>Bug fix in mother pointer of multiparton interactions in |
---|
| 917 | diffractive systems.</li> |
---|
| 918 | |
---|
| 919 | </ul> |
---|
| 920 | </li> |
---|
| 921 | |
---|
| 922 | <li>8.142: 15 August 2010 |
---|
| 923 | <ul> |
---|
| 924 | |
---|
| 925 | <li>The strategy for setting up tune values has been changed. |
---|
| 926 | Previously the <code>Tune:ee</code> and <code>Tune:pp</code> |
---|
| 927 | settings were only interpreted during the |
---|
| 928 | <code>Pythia::init(...)</code> stage. Now they are interpreted |
---|
| 929 | as soon as they are read. Specifically this means that it is |
---|
| 930 | possible to override any of the tune parameters by putting new |
---|
| 931 | commands below <code>Tune:ee</code> and <code>Tune:pp</code> |
---|
| 932 | in the <code>Pythia::readFile(...)</code> configuration file |
---|
| 933 | or in the list of <code>Pythia::readString(...)</code> commands. |
---|
| 934 | <br/>As a consequence of this change, the public |
---|
| 935 | <code>Pythia::initTunes(...)</code> method has been replaced by |
---|
| 936 | two private <code>Settings::initTuneEE(...)</code> and |
---|
| 937 | <code>Settings::initTunePP(...)</code> methods. |
---|
| 938 | <br/>If <code>Tune:ee</code> or <code>Tune:pp</code> are |
---|
| 939 | nonvanishing by default, then the corresponding tune variables |
---|
| 940 | are set also from the <code>Pythia</code> constructor, before any |
---|
| 941 | user changes are possible. Currently this is not relevant. |
---|
| 942 | </li> |
---|
| 943 | |
---|
| 944 | <li>Bug fix in the setup of the <code>Tune:pp = 5</code> and |
---|
| 945 | <code>= 6</code> options, which meant that diffractive cross |
---|
| 946 | sections were not reduced as advertised.</li> |
---|
| 947 | |
---|
| 948 | <li>The default value of <code>MultipartonInteractions:pT0Ref</code> |
---|
| 949 | has been slightly reduced so as to give a somewhat improved |
---|
| 950 | default description. It is not intended as a replacement for the |
---|
| 951 | specific tunes, however.</li> |
---|
| 952 | |
---|
| 953 | <li>Some comparisons between tunes and data, obtained with the |
---|
| 954 | Rivet package, have been posted on |
---|
| 955 | <a href="http://home.thep.lu.se/~richard/pythia81/"> |
---|
| 956 | http://home.thep.lu.se/~richard/pythia81/</a>. |
---|
| 957 | Further improvements can be expected from future Professor-based |
---|
| 958 | tunes. The current set of 2C, 2M, 3C and 3M "draft tunes" have |
---|
| 959 | deliberately been chosen different also to explore a range of |
---|
| 960 | possibilities. One not visible in the plots is the fraction |
---|
| 961 | of single and double diffractive events in the inelastic cross |
---|
| 962 | section. This is 32% in 2C and 2M, while it was reduced to |
---|
| 963 | 21% in 3C and 3M, and a recent ATLAS study (ATLAS-CONF-2010-048) |
---|
| 964 | would suggest 28+-4%.</li> |
---|
| 965 | |
---|
| 966 | <li>Minor changes in <code>TimeShower</code> and |
---|
| 967 | <code>SpaceShower</code>, as protection if the <i>c</i> or |
---|
| 968 | <i>b</i> masses are set small.</li> |
---|
| 969 | |
---|
| 970 | <li>Bug fix in <code>SpaceShower</code>, for case when <i>phi</i> |
---|
| 971 | angle selection is biased to take into account interference effects. |
---|
| 972 | </li> |
---|
| 973 | |
---|
| 974 | <li>The <code>SigmaProcess::convertM2()</code> method now has |
---|
| 975 | been implemented also for <i>2 -> 1</i> processes, so that it is |
---|
| 976 | possible to provide the squared matrix element instead of |
---|
| 977 | <i>sigmaHat</i> for semi-internal processes. A fixed-width |
---|
| 978 | Breit-Wigner is also inserted, since the matrix element is supposed |
---|
| 979 | not to include it.</li> |
---|
| 980 | |
---|
| 981 | <li>New method <code>SigmaProcess::setupForME()</code> does an |
---|
| 982 | extended conversion from the internal kinematics to an almost |
---|
| 983 | equivalent one, better adapted to the mass conventions of matrix-element |
---|
| 984 | caclulation programs, such as massive incoming <i>b</i> quarks. |
---|
| 985 | New flags allow to determine whether the <i>c</i>, <i>b</i>, |
---|
| 986 | <i>mu</i> and <i>tau</i> should be considered massless or not |
---|
| 987 | in the calculations.</li> |
---|
| 988 | |
---|
| 989 | <li>Two new friend methods <code>table</code> of the <code>Hist</code> |
---|
| 990 | class allow to print a table with three columns, the first for the |
---|
| 991 | (common!) <i>x</i> values and the other two for the respective |
---|
| 992 | histogram values. A new method <code>takeSqrt</code> for the square |
---|
| 993 | root of histogram bin contents. |
---|
| 994 | </li> |
---|
| 995 | |
---|
| 996 | </ul> |
---|
| 997 | </li> |
---|
| 998 | |
---|
| 999 | <li>8.145: 10 November 2010 |
---|
| 1000 | <ul> |
---|
| 1001 | |
---|
| 1002 | <li><code>Couplings</code> is defined in <code>StandardModel.h</code> |
---|
| 1003 | as a derived class of <code>coupSM</code> and has only one extra flag: |
---|
| 1004 | <code>isSUSY</code> to check presence of extra couplings.Changed all |
---|
| 1005 | pointers <code>CoupSM*</code> to <code>Couplings*</code> and removed |
---|
| 1006 | explicit references to <code>CoupSUSY*</code>. The <code>coupSUSY</code> |
---|
| 1007 | object is only initialised if SUSY couplings are present. The new pointer |
---|
| 1008 | <code>couplingsPtr</code> points either to only SM couplings or SM+SUSY |
---|
| 1009 | couplings based on SLHA data.</li> |
---|
| 1010 | |
---|
| 1011 | <li>New files <code>SusyResonanceWidths.h/cc</code> contains the |
---|
| 1012 | <code>SusyResonanceWidths</code> class, which inherits from |
---|
| 1013 | <code>ResonanceWidths</code> but typecasts the <code>couplingsPtr</code> |
---|
| 1014 | to <code>(CoupSUSY*) coupSUSYPtr</code>. This is the base class for |
---|
| 1015 | all SUSY resonances. It contains the <code>ResonanceSquark</code> class |
---|
| 1016 | for all squark decays. A new flag <code>SLHA:useDecayTable</code> |
---|
| 1017 | to check if internal widths should be overwritten by those read in |
---|
| 1018 | via SLHA.</li> |
---|
| 1019 | |
---|
| 1020 | <li>Added new functionality to <code>SusyLesHouches</code> for read-in |
---|
| 1021 | of generic user blocks in the SLHA format, along with methods to |
---|
| 1022 | extract parameters from them with typecasting controlled by the user. |
---|
| 1023 | Intended for use with user-written semi-internal processes.</li> |
---|
| 1024 | |
---|
| 1025 | <li>Added <code>Sigma1qq2antisquark</code> cross section.</li> |
---|
| 1026 | |
---|
| 1027 | <li>Some new flags and modes in the <code>SUSY</code> and |
---|
| 1028 | <code>SLHA</code> series offer further functionality.</li> |
---|
| 1029 | |
---|
| 1030 | <li>Several further changes as a consequence of the upgrade of the SUSY |
---|
| 1031 | machinery.</li> |
---|
| 1032 | |
---|
| 1033 | <li>Bug/typo fixes in rotation matrices for SUSY couplings and for the |
---|
| 1034 | processes <code>qqbar2squarkantisquark</code>, |
---|
| 1035 | <code>qq2squarksquark</code> and more.</li> |
---|
| 1036 | |
---|
| 1037 | <li>Improved handling of colour junctions. Added new example program |
---|
| 1038 | <code>main72.cc</code>, to illustrate read-in of color junction |
---|
| 1039 | structures via LHEF (<code>main72.lhe</code>). The example used is SUSY |
---|
| 1040 | with RPV.</li> |
---|
| 1041 | |
---|
| 1042 | <li>New Tune 4C introduced as <code>Tune:pp = 5</code>. The more crude |
---|
| 1043 | (non-)tunes 3C and 3M are removed.</li> |
---|
| 1044 | |
---|
| 1045 | <li>New methods <code>Settings::getFlagMap(...)</code>, |
---|
| 1046 | <code>Settings::getModeMap(...)</code>, |
---|
| 1047 | <code>Settings::getParmMap(...)</code> and |
---|
| 1048 | <code>Settings::getWordMap(...)</code> allows to return a map of all |
---|
| 1049 | settings of the respective type that contain a specific string |
---|
| 1050 | in its name. |
---|
| 1051 | </li> |
---|
| 1052 | |
---|
| 1053 | <li>Improved description of excited <i>g^*/KK-gluon^*</i> production |
---|
| 1054 | in the <code>Sigma1qqbar2KKgluonStar</code> and |
---|
| 1055 | <code>ResonanceKKgluon</code> classes.</li> |
---|
| 1056 | |
---|
| 1057 | <li>Possibility added to let Hidden-Valley <i>gamma_v</i> have |
---|
| 1058 | a nonero mass and decay by mixing with the ordinary photon. |
---|
| 1059 | Still experimental.</li> |
---|
| 1060 | |
---|
| 1061 | <li>Minor bug fix in handling of three-body phase space.</li> |
---|
| 1062 | |
---|
| 1063 | <li>Minor correction in <code>Sigma2ffbar2TEVffbar</code> class.</li> |
---|
| 1064 | |
---|
| 1065 | <li>Bug fix for decays of <i>W'</i> to a pair of heavy fermions when |
---|
| 1066 | <i>gV != gA</i>. Thanks to M. Chizhov, see arXiv:0705.3944. </li> |
---|
| 1067 | |
---|
| 1068 | <li>Restore the older EHLQ-based encoding of the <i>f fbar -> Z W</i> |
---|
| 1069 | cross section, which was changed in version 8.140, since comparisons |
---|
| 1070 | with Madgraph gives much better agreement with it than with the |
---|
| 1071 | expression of Brown, Sahdev and Mikaelian.</li> |
---|
| 1072 | |
---|
| 1073 | <li>The <code>HepMCInterface</code> now also stores colour flow |
---|
| 1074 | information for coloured particles.</li> |
---|
| 1075 | |
---|
| 1076 | <li>Pointer to <code>Couplings</code> made available for particle |
---|
| 1077 | decays.</li> |
---|
| 1078 | |
---|
| 1079 | <li>Minor update in <code>main61.cc</code> for more elegant usage |
---|
| 1080 | of FastJet, as suggested by Gregory Soyez.</li> |
---|
| 1081 | |
---|
| 1082 | </ul> |
---|
| 1083 | </li> |
---|
| 1084 | |
---|
| 1085 | <li>8.150: 20 April 2011 |
---|
| 1086 | <ul> |
---|
| 1087 | |
---|
| 1088 | <li>Tune 4C is made default. It is based on first comparisons with |
---|
| 1089 | LHC data [<a href="Bibliography.php" target="page">Cor10a</a>], and has also been checked independently |
---|
| 1090 | [<a href="Bibliography.php" target="page">Buc11</a>] to give reasonable agreement with many distributions. |
---|
| 1091 | </li> |
---|
| 1092 | |
---|
| 1093 | <li>The description of <i>tau</i> lepton decays has been significantly |
---|
| 1094 | enhanced, to include helicity information related to the production |
---|
| 1095 | process and hadronic currents fitted to data. A complete writeup is |
---|
| 1096 | in preparation [<a href="Bibliography.php" target="page">Ilt11</a>]. A new flag is introduced to revert |
---|
| 1097 | to the old behaviour, for cross-checks, see |
---|
| 1098 | <?php $filepath = $_GET["filepath"]; |
---|
| 1099 | echo "<a href='ParticleDecays.php?filepath=".$filepath."' target='page'>";?>Particle Decays</a>. |
---|
| 1100 | The new tau decay machinery is on by default. |
---|
| 1101 | </li> |
---|
| 1102 | |
---|
| 1103 | <li>A new option <code>MultipartonInteractions:bProfile = 4</code> has |
---|
| 1104 | been introduced for the impact-parameter profile of protons in the |
---|
| 1105 | <?php $filepath = $_GET["filepath"]; |
---|
| 1106 | echo "<a href='MultipartonInteractions.php?filepath=".$filepath."' target='page'>";?>Multiparton Interactions</a> |
---|
| 1107 | framework, wherein low-<i>x</i> partons are spread over a larger area |
---|
| 1108 | than high-<i>x</i> ones, see [<a href="Bibliography.php" target="page">Cor11</a>]. A new method |
---|
| 1109 | <code>Info::eMPI(i)</code> gives back the enhancement factor related to |
---|
| 1110 | the <code>i</code>'th interaction. The impact-parameter profile can now |
---|
| 1111 | be selected separately for <?php $filepath = $_GET["filepath"]; |
---|
| 1112 | echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>diffraction</a>, |
---|
| 1113 | but without a <code>bProfile = 4</code> option. |
---|
| 1114 | </li> |
---|
| 1115 | |
---|
| 1116 | <li>The possibility of "hadronization" in the |
---|
| 1117 | <?php $filepath = $_GET["filepath"]; |
---|
| 1118 | echo "<a href='HiddenValleyProcesses.php?filepath=".$filepath."' target='page'>";?>Hidden Valley</a> sector |
---|
| 1119 | has been added as a new option <code>HiddenValley:fragment = on</code>. |
---|
| 1120 | This is based on a copy of the standard string fragmentation framework, |
---|
| 1121 | but with the option of a completely separate "flavour" sector, and |
---|
| 1122 | separately tunable longitudinal fragmentation functions and transverse |
---|
| 1123 | momenta. For now only a simple flavour scenario is provided, where |
---|
| 1124 | flavour-diagonal mesons can decay back into the normal visible sector |
---|
| 1125 | while off-diagonal ones remain hidden. A writeup of the model is in |
---|
| 1126 | preparation [<a href="Bibliography.php" target="page">Car11</a>]. Also some further Hidden Valley options |
---|
| 1127 | have been added.</li> |
---|
| 1128 | |
---|
| 1129 | <li>Included possibility in <code>TimeShower</code> for QCD dipoles to |
---|
| 1130 | have an adjustible normalization factor, via the new |
---|
| 1131 | <code>bool isFlexible</code> and <code>double flexFactor</code> |
---|
| 1132 | properties of <code>class TimeDipoleEnd</code>. This flexibility is used |
---|
| 1133 | to treat radiation off colour topologies with epsilon tensors, in |
---|
| 1134 | particular colour junctions which have all their partons in the |
---|
| 1135 | final state. (An example is the BNV-SUSY decay ~chi0→uds.) For |
---|
| 1136 | such topologies, the new treatment in PYTHIA 8 is that a |
---|
| 1137 | half-strength dipole is spanned between all combinations of |
---|
| 1138 | final-state quarks. For junctions with an incoming (anti)colour line (such |
---|
| 1139 | as in the BNV-SUSY decay ~t*→cb), a full-strength dipole is |
---|
| 1140 | instead spanned between the two daughters, with no radiation from the |
---|
| 1141 | decaying object (in its CM). As will be described in a fortcoming |
---|
| 1142 | paper with N. Desai, this should give the |
---|
| 1143 | closest possible correspondence to the radiation patterns exhibited |
---|
| 1144 | by higher-order matrix elements for this type of process.</li> |
---|
| 1145 | |
---|
| 1146 | <li>Corrected harmless bugs in <code>ProcessLevel::findJunctions</code> |
---|
| 1147 | which caused junctions of types 3 and 4 (i.e., junctions with 1 |
---|
| 1148 | incoming color tag) to sometimes be incorrectly classified as types |
---|
| 1149 | 1 and 2 (with all color tags outgoing), respectively. |
---|
| 1150 | Since the parity (even/odd) of the junction kind was still correct, |
---|
| 1151 | however, this did not cause any problems at the hadronization |
---|
| 1152 | stage.</li> |
---|
| 1153 | |
---|
| 1154 | <li>The junction-finder in <code>ProcessLevel::findJunctions</code> |
---|
| 1155 | has been made more stable, and the following ordering of the color |
---|
| 1156 | tags returned by <code>Event::endColJunction(iJun, iLeg)</code> is |
---|
| 1157 | now enforced: for junction kinds 3 and 4 (one tag |
---|
| 1158 | incoming), <code>iLeg = 0</code> will return the |
---|
| 1159 | incoming tag, while for kinds 5 and 6 (two tags incoming), |
---|
| 1160 | <code>iLeg = 0</code> and <code>iLeg = 1</code> will return the |
---|
| 1161 | incoming tags. Apart from this ordering, the color tags are |
---|
| 1162 | ordered in ascending color tag number.</li> |
---|
| 1163 | |
---|
| 1164 | <li>Declarations of friend functions moved to sit outside the class |
---|
| 1165 | it befriends. Thanks to Axel Naumann for pointing out the incorrect |
---|
| 1166 | previous construction.</li> |
---|
| 1167 | |
---|
| 1168 | <li>The <code>rootexample</code> subdirectory becomes |
---|
| 1169 | <code>rootexamples</code> as the old example is split into two, |
---|
| 1170 | with improved documentation to clarify usage. Thanks to Axel Naumann |
---|
| 1171 | and Bernhard Meirose for the new code.</li> |
---|
| 1172 | |
---|
| 1173 | <li>In the Les Houches Event File machinery, input type has been |
---|
| 1174 | changed from <code>ifstream</code> to <code>istream</code> for more |
---|
| 1175 | flexibility.</li> |
---|
| 1176 | |
---|
| 1177 | <li>R-hadron handling is largely implemented, see the |
---|
| 1178 | <?php $filepath = $_GET["filepath"]; |
---|
| 1179 | echo "<a href='RHadrons.php?filepath=".$filepath."' target='page'>";?>R-hadrons</a> page, although some aspects |
---|
| 1180 | still need polishing. A new class <code>RHadrons</code> takes |
---|
| 1181 | care of the hadronization and decay. Particle data have been added |
---|
| 1182 | for R-hadrons containing a gluino, stop or sbottom, but could |
---|
| 1183 | alternatively be used for other long-lived coloured particles. |
---|
| 1184 | Thanks to Bernhard Meirose for support. |
---|
| 1185 | </li> |
---|
| 1186 | |
---|
| 1187 | <li>Calculations of SUSY decay widths included by |
---|
| 1188 | N. Desai, contained in the new source |
---|
| 1189 | files <code>SusyResonanceWidth.cc</code> |
---|
| 1190 | and </code>.h</code>. Validation and addition of more modes is still in |
---|
| 1191 | progress, so this implementation should be considered preliminary |
---|
| 1192 | for now. For a list of available modes, see |
---|
| 1193 | the <?php $filepath = $_GET["filepath"]; |
---|
| 1194 | echo "<a href='SUSYProcesses.php?filepath=".$filepath."' target='page'>";?>SUSY Processes</a> page. |
---|
| 1195 | </li> |
---|
| 1196 | |
---|
| 1197 | <li>A first implementation of the SLHA-based QNUMBERS interface for |
---|
| 1198 | defining new exotic particles has been |
---|
| 1199 | included. See [<a href="Bibliography.php" target="page">Alw07</a>] and |
---|
| 1200 | the <?php $filepath = $_GET["filepath"]; |
---|
| 1201 | echo "<a href='SUSYLesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>SUSY Les Houches Accord</a> |
---|
| 1202 | page. </li> |
---|
| 1203 | |
---|
| 1204 | <li>Read-in of LHEF events containing Baryon Number Violating vertices |
---|
| 1205 | has been included, using colour junctions, see |
---|
| 1206 | the <?php $filepath = $_GET["filepath"]; |
---|
| 1207 | echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>Event Record</a> page. The advanced |
---|
| 1208 | shower model taking into account the full colour structure of such |
---|
| 1209 | events, developed by N. Desai and described above, |
---|
| 1210 | is turned on by default in such events. |
---|
| 1211 | Several test cases were used to |
---|
| 1212 | validate this implementation, but it is possible that problems could |
---|
| 1213 | still exist for some cases. Feedback is welcome. Thanks to |
---|
| 1214 | the MadGraph authors for providing several test cases.</li> |
---|
| 1215 | |
---|
| 1216 | <li>Some first steps taken to allow events containing colour sextets, |
---|
| 1217 | e.g., from semi-internal processes or LHEF interfaces, and/or from |
---|
| 1218 | SLHA <code>DECAY</code> tables. New |
---|
| 1219 | <code>colType</code> codes 3 and -3 are introduced to describe |
---|
| 1220 | sextets and antisextets, respectively. The state of the current |
---|
| 1221 | implementation is that hard processes containing such states can be |
---|
| 1222 | read in and decays generated (via <code>DECAY</code> tables). Parton |
---|
| 1223 | showers can be added, but the sextets themselves do not, as yet, |
---|
| 1224 | shower, and any undecayed sextets remaining at the hadronization |
---|
| 1225 | stage would lead to unpredictable problems if hadronization is |
---|
| 1226 | switched on. Thanks to J. Alwall for help with testing |
---|
| 1227 | this implementation. |
---|
| 1228 | </li> |
---|
| 1229 | |
---|
| 1230 | <li>The functionality of the SLHA SUSY/BSM interface (see |
---|
| 1231 | the <?php $filepath = $_GET["filepath"]; |
---|
| 1232 | echo "<a href='SUSYLesHouches.php?filepath=".$filepath."' target='page'>";?>SUSY Les Houches</a> page) has been |
---|
| 1233 | extended so that copies of all <code>BLOCK</code>s are now stored |
---|
| 1234 | internally as |
---|
| 1235 | strings, regardless of whether they correspond to "official" SLHA |
---|
| 1236 | blocks or not. Their contents can subsequently be queried by a set |
---|
| 1237 | of new templated member functions of the |
---|
| 1238 | class <code>SusyLesHouches</code>. Available query functions so far |
---|
| 1239 | include |
---|
| 1240 | <br/><code>template <class T> bool getEntry(string, T&);</code>, |
---|
| 1241 | <br/><code>template <class T> bool getEntry(string, int, T&);</code>, |
---|
| 1242 | <br/><code>template <class T> bool getEntry(string, int, int, T&); |
---|
| 1243 | </code>, and |
---|
| 1244 | <br/><code>template <class T> bool getEntry(string, int, |
---|
| 1245 | int, int, T&);</code>, |
---|
| 1246 | <br/>where the type of |
---|
| 1247 | the argument used in the call determines how to read the block |
---|
| 1248 | entries. Thus, if an LHEF, SLHA, or other card file is read in by |
---|
| 1249 | PYTHIA, the contents of any <code>BLOCK</code> in that file can |
---|
| 1250 | subsequently be queried run-time using these functions. This is |
---|
| 1251 | used, e.g., in the new interface between MADGRAPH 5 and PYTHIA |
---|
| 1252 | 8. Thanks to the MADGRAPH team, and to J. Alwall in particular, for |
---|
| 1253 | help and debug on this new implementation. |
---|
| 1254 | </li> |
---|
| 1255 | |
---|
| 1256 | </ul> |
---|
| 1257 | </li> |
---|
| 1258 | |
---|
| 1259 | <li>8.153: 10 August 2011 |
---|
| 1260 | <ul> |
---|
| 1261 | |
---|
| 1262 | <li>The setup of tunes has been modified, see the |
---|
| 1263 | <?php $filepath = $_GET["filepath"]; |
---|
| 1264 | echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tunes</a> page for details. Specifically |
---|
| 1265 | the <code>Tune:ee</code> and <code>Tune:pp</code> modes have |
---|
| 1266 | acquired a new option <code>-1</code> for a forced restore to the |
---|
| 1267 | default values of all settings used in the respective kind of |
---|
| 1268 | tunes.</li> |
---|
| 1269 | |
---|
| 1270 | <li>The code for handling multiparton interactions in the scenario with |
---|
| 1271 | an <i>x</i>-dependent width of the Gaussian matter profile |
---|
| 1272 | [<a href="Bibliography.php" target="page">Cor11</a>], has been improved and updated. Tune 4Cx, which |
---|
| 1273 | is based on this option, has been added as a further tune option.</li> |
---|
| 1274 | |
---|
| 1275 | <li>A possibility to bias the phase-space selection has been added, |
---|
| 1276 | whereby some phase space regions can be oversampled, which is |
---|
| 1277 | compensated by assigning a weight to each event. |
---|
| 1278 | A new set of methods have been added to the <code>UserHooks</code> |
---|
| 1279 | class to allow users to program how to bias the selection.</li> |
---|
| 1280 | |
---|
| 1281 | <li>New options added so that matrix-element corrections can be |
---|
| 1282 | switched off after the first branching in ISR or FSR.</li> |
---|
| 1283 | |
---|
| 1284 | <li>Some new <code>Info</code> methods have been added to store |
---|
| 1285 | information on latest ISR branching. The <code>SpaceShower</code> |
---|
| 1286 | class has also been corrected so that the latest <i>z = 1/2</i> |
---|
| 1287 | when not defined by history. This avoids undefined values for |
---|
| 1288 | azimuthal asymmetries. Thanks to Stefan Prestel for finding and |
---|
| 1289 | sorting out this problem.</li> |
---|
| 1290 | |
---|
| 1291 | <li>The <code>Pythia::forceHadronLevel()</code> method now takes |
---|
| 1292 | an argument that optionally means that existing junction information |
---|
| 1293 | is not overwritten. Thanks to Leif Lönnblad for pointing out |
---|
| 1294 | the usefulness of this.</li> |
---|
| 1295 | |
---|
| 1296 | <li>For particle decays to a varying number of hadrons the multiplicity |
---|
| 1297 | increase with mass has been somewhat reduced, and especially for |
---|
| 1298 | <code>meMode = 23</code> a separate even slower increase has been |
---|
| 1299 | introduced.</li> |
---|
| 1300 | |
---|
| 1301 | <li>New possibility to force the tau polarization.</li> |
---|
| 1302 | |
---|
| 1303 | <li>Bug fix for the special case in which events containing SUSY |
---|
| 1304 | particles are generated without proper initialization of SUSY decays. |
---|
| 1305 | This can happen, e.g., if events containing SUSY particles are read |
---|
| 1306 | in via external LHEF files, if those files do not contain readable |
---|
| 1307 | SLHA spectra in their headers. In this case, a failed attempt to |
---|
| 1308 | generate sparticle decays with ill-defined couplings previously |
---|
| 1309 | led to crashes. The program now reverts to the old behaviour, |
---|
| 1310 | based on static decay tables, in such cases, with the default |
---|
| 1311 | being to decay all sparticles to gravitino + particle. An error |
---|
| 1312 | message stating that the full SUSY treatment has been switched |
---|
| 1313 | off and why is also issued. Thanks to N. Desai for this fix.</li> |
---|
| 1314 | |
---|
| 1315 | <li>The R-hadron machinery has been completed.</li> |
---|
| 1316 | |
---|
| 1317 | <li>Minor change in timelike showers: gluons which fall below the |
---|
| 1318 | <i>pTmin</i> cutoff by the correction for mass effects are now |
---|
| 1319 | eliminated, while previously they were kept. This reduces the |
---|
| 1320 | number of gluons somewhat, but has no significant effects on the |
---|
| 1321 | hadronic final state. (Prompted by R-hadron studies, where big mass |
---|
| 1322 | effects else give bothersome low-energy gluons.)</li> |
---|
| 1323 | |
---|
| 1324 | <li>Corrected typos in two of the Upsilon wave function matrix |
---|
| 1325 | elements, <code>Bottomonium:OUpsilon3P08</code> and |
---|
| 1326 | <code>Bottomonium:Ochib03P01</code>. Thanks to Beate Heinemann for |
---|
| 1327 | pointing it out.</li> |
---|
| 1328 | |
---|
| 1329 | <li>Implemented <i>f*</i> decay angle in <i>f f -> f f*</i> processes, |
---|
| 1330 | and fixed some bugs for the same process. Thanks to Piyali Banerjee |
---|
| 1331 | for tests.</li> |
---|
| 1332 | |
---|
| 1333 | <li>Introduce possibility to separate production channels for |
---|
| 1334 | TeV-sized extra dimensions, and a small code correction. Thanks to |
---|
| 1335 | Noam Hod for code contribution.</li> |
---|
| 1336 | |
---|
| 1337 | <li>Bug fix for neutrino beams: since neutrinos are always lefthanded |
---|
| 1338 | there should be a factor 2 in the cross section, relative to charged |
---|
| 1339 | leptons, from the non-need to average over incoming spin states. This |
---|
| 1340 | is now fixed by introducing a new PDF class <code>NeutrinoPoint</code> |
---|
| 1341 | for (unresolved) neutrinos, with normalization 2 rather than 1 for |
---|
| 1342 | charged leptons. Thanks to Ryosuke Sato.</li> |
---|
| 1343 | |
---|
| 1344 | <li>Bug fix for some (rarely used) particle settings, which could not |
---|
| 1345 | be changed by users because they were read too early. Thanks to |
---|
| 1346 | Andrew Altheimer and Gustaaf Brooijmans.</li> |
---|
| 1347 | |
---|
| 1348 | <li>Bug fix in handling of <code>tau</code> decays, where setting of |
---|
| 1349 | decay vertices could write outside memory. Thanks to Steven Schramm.</li> |
---|
| 1350 | |
---|
| 1351 | <li>Minor expansion of the <code>BeamParticle</code> constructor.</li> |
---|
| 1352 | |
---|
| 1353 | <li>Minor bug fix in CTEQ 6L for uninitialized variables.</li> |
---|
| 1354 | |
---|
| 1355 | <li>Minor bug fix in fragmentation flavour combination to hadron.</li> |
---|
| 1356 | |
---|
| 1357 | <li>Some updates of the documentation, including new pages on |
---|
| 1358 | MadGraph 5 as a generator for semi-internal processes (thanks to |
---|
| 1359 | Johan Alwall) and on RIVET interfacing.</li> |
---|
| 1360 | |
---|
| 1361 | <li>Minor improvements of ROOT- and HepMC-related code and documentation.</li> |
---|
| 1362 | |
---|
| 1363 | <li>Some cleanup of code.</li> |
---|
| 1364 | |
---|
| 1365 | </ul> |
---|
| 1366 | </li> |
---|
| 1367 | |
---|
| 1368 | <li>8.157: 10 November 2011 |
---|
| 1369 | <ul> |
---|
| 1370 | |
---|
| 1371 | <ii>StefanPrestel joins as new member of the PYTHIA author team. |
---|
| 1372 | He is mainly working on matching/merging issues, and has contributed |
---|
| 1373 | the CKKW-L machinery mentioned below.</li> |
---|
| 1374 | |
---|
| 1375 | <li>Merging capabilities according to the CKKW-L scheme [<a href="Bibliography.php" target="page">Lon11</a>] |
---|
| 1376 | have been added, see the new |
---|
| 1377 | <?php $filepath = $_GET["filepath"]; |
---|
| 1378 | echo "<a href='MatrixElementMerging.php?filepath=".$filepath."' target='page'>";?>Matrix Element Merging</a> |
---|
| 1379 | page. It involves new classes to reconstruct and select how a |
---|
| 1380 | matrix-element-generated partonic configuration could have been obtained |
---|
| 1381 | by the PYTHIA evolution, and to perform trial showers (using a new |
---|
| 1382 | copy of the normal parton-level machinery) that introduce the appropriate |
---|
| 1383 | Sudakov suppression factors. New examples to illustrate various |
---|
| 1384 | common tasks are found in <code>main81.cc</code>, <code>main82.cc</code>, |
---|
| 1385 | <code>main83.cc</code> and <code>main84.cc</code>.</li> |
---|
| 1386 | |
---|
| 1387 | <li>The <code>main71.cc</code> program is now generalised for reading |
---|
| 1388 | in arbitrary POWHEG LHE files, to implement a smooth matching between NLO |
---|
| 1389 | matrix elements and the PYTHIA parton showers. Cuts are made on both |
---|
| 1390 | ISR and FSR emissions, while previously only ISR was covered. The key |
---|
| 1391 | assumptions are the <i>pT</i> definitions used for ISR and FSR, but several |
---|
| 1392 | further options are available, as documented in the <code>main71.cmnd</code> |
---|
| 1393 | file. Work is still ongoing to pick the best default options. </li> |
---|
| 1394 | |
---|
| 1395 | <li>Several expansions of the <code>UserHooks</code> class. |
---|
| 1396 | For both <code>doVetoFSREmission</code> and <code>doVetoISREmission</code> |
---|
| 1397 | a new argument <code>iSys</code> labels the system within which the |
---|
| 1398 | radiation occurs. For <code>doVetoFSREmission</code> a further argument |
---|
| 1399 | <code>inResonance</code> distinguishes FSR in resonance |
---|
| 1400 | decays from that in the hard process itself. New methods |
---|
| 1401 | <code>canVetoMPIEmission</code> and <code>doVetoMPIEmission</code> |
---|
| 1402 | have been added to veto multiparton interactions in the same way as |
---|
| 1403 | FSR and ISR. In <code>biasSelectionBy</code> at times incorrect values |
---|
| 1404 | for <code>inEvent</code> has been corrected. Also some systematization |
---|
| 1405 | of the use of <code>const</code>.</li> |
---|
| 1406 | |
---|
| 1407 | <li>A new model for hadron scattering is introduced, still at an early |
---|
| 1408 | stage and therefore more intended for internal development than for the |
---|
| 1409 | normal user. The basic idea is that a high-energy <i>pp</i> collision |
---|
| 1410 | involves the fragmentation of multiparton strings that overlap in space |
---|
| 1411 | (and time). Also the produced hadrons therefore initially overlap, and |
---|
| 1412 | there is a strong likelihood that hadrons can scatter against each other |
---|
| 1413 | until the system has expanded sufficiently. This can e.g. increase the |
---|
| 1414 | transverse momentum of heavier hadrons at the expense of lighter ones. |
---|
| 1415 | </li> |
---|
| 1416 | |
---|
| 1417 | <li>A new jet finder <code>SlowJet</code> offers simple access to the |
---|
| 1418 | inclusive <i>kT</i>, anti-<i>kT</i>, and Cambridge/Aachen |
---|
| 1419 | algorithms in a cylindrical coordinate frame. The jet reconstruction |
---|
| 1420 | is then based on sequential recombination with progressive removal, |
---|
| 1421 | using the <i>E</i> recombination scheme. The minimalistic |
---|
| 1422 | <code>SlowJet</code> code is much slower than <code>FastJet</code> |
---|
| 1423 | [<a href="Bibliography.php" target="page">Cac06</a>], and contains less options, but reconstructs the same |
---|
| 1424 | jets if run under identical conditions. For details see the |
---|
| 1425 | <?php $filepath = $_GET["filepath"]; |
---|
| 1426 | echo "<a href='EventAnalysis.php?filepath=".$filepath."' target='page'>";?>Event Analysis</a> page.</li> |
---|
| 1427 | |
---|
| 1428 | <li>Starting in gcc 4.6, it is possible to switch off specific warnings |
---|
| 1429 | around specific blocks of code. Although version 4.6 is some way off |
---|
| 1430 | from being commonly found, this option has now been introduced to switch |
---|
| 1431 | off <code>-Wshadow</code> warnings in <code>HepMCInterface.cc</code>. |
---|
| 1432 | For other compilers, or earlier versions of gcc, the old behaviour |
---|
| 1433 | is retained.</li> |
---|
| 1434 | |
---|
| 1435 | <li>Support for reading in gzipped LHEFs has been added in the |
---|
| 1436 | <code>LesHouches</code> and <code>SusyLesHouches</code> classes. |
---|
| 1437 | This also affects <code>configure</code> and <code>Makefile</code>s. |
---|
| 1438 | Unless explicitly enabled, it should not affect anything. |
---|
| 1439 | If enabled, it relies on the Boost and zlib libraries to function, |
---|
| 1440 | so paths to these must be set appropriately, see the |
---|
| 1441 | <code>README</code> file for details. The Boost header files can |
---|
| 1442 | give very many shadow warnings, so <code>-Wshadow</code> is disabled |
---|
| 1443 | if gzip support is enabled, as described above.</li> |
---|
| 1444 | |
---|
| 1445 | <li>Introduce use of the <code>HEPMC_HAS_UNITS</code> environment |
---|
| 1446 | variable in the <code>HepMCInterface.cc</code> and <code>main32.cc</code> |
---|
| 1447 | codes to automatically check whether GeV and mm can be set as relevant |
---|
| 1448 | units. If yes, then it is set in <code>main32.cc</code>. If no, |
---|
| 1449 | a conversion from GeV to MeV is done explicitly in |
---|
| 1450 | <code>HepMCInterface.cc</code>. Note that, for early HepMC versions, |
---|
| 1451 | this means a change of behaviour. Thanks to Andy Buckley.</li> |
---|
| 1452 | |
---|
| 1453 | <li>A new method <code>Info::lhaStrategy()</code> returns the |
---|
| 1454 | Les Houches event weighting strategy where relevant, and 0 where not. |
---|
| 1455 | For the strategies <i>+-4</i> the event weight and sum, |
---|
| 1456 | <code>Info::weight()</code> and <code>Info::weightSum()</code>, |
---|
| 1457 | is now in units of pb at output, as it should be at input. |
---|
| 1458 | (While internally mb is used.)</li> |
---|
| 1459 | |
---|
| 1460 | <li>New flag <code>Check:abortIfVeto</code> allows the user to |
---|
| 1461 | resume control over execution in case of a veto in the event |
---|
| 1462 | generation process.</li> |
---|
| 1463 | |
---|
| 1464 | <li>New method <code>Event::at(i)</code> returns reference to |
---|
| 1465 | <code>i</code>'th particle in the event record.</li> |
---|
| 1466 | |
---|
| 1467 | <li>Introduce the Fermi constant as one of the Standard Model |
---|
| 1468 | parameters.</li> |
---|
| 1469 | |
---|
| 1470 | <li>Included automatic pre-initialization of SLHA blocks MASS and |
---|
| 1471 | SMINPUTS using PYTHIA's SM parameters and particle data table |
---|
| 1472 | values.</li> |
---|
| 1473 | |
---|
| 1474 | <li>SUSY: added sleptons (and sneutrinos) as resonances. |
---|
| 1475 | Corrected 2-body decay widths of gluinos, squarks and gauginos. |
---|
| 1476 | Added sleptonic decay modes to gaugino decays. |
---|
| 1477 | Implemented 2-body decays of sleptons (and sneutrinos) |
---|
| 1478 | into sleptons/leptons/gauginos. Corrected slepton couplings (they |
---|
| 1479 | now look exactly like squark couplings, using a 6x6 slepton mixing |
---|
| 1480 | matrix).</li> |
---|
| 1481 | |
---|
| 1482 | <li>New parameter <code>Diffraction:probMaxPert</code> introduce to |
---|
| 1483 | give more flexibility in transition from a nonperturbative to a |
---|
| 1484 | perturbative description of a diffractive system.</li> |
---|
| 1485 | |
---|
| 1486 | <li>Bug corrected in <code>SigmaEW.cc</code>, for the process |
---|
| 1487 | <code>WeakSingleBoson:ffbar2ffbar(s:gm)</code>. Previously, all outgoing |
---|
| 1488 | quark flavours in this process were erroneously assigned ID code 5 |
---|
| 1489 | (b quarks). This has now been corrected so the proper ratios are |
---|
| 1490 | obtained, with <i>u : c : d : s : b = 4 : 4 : 1 : 1 : 1</i>, |
---|
| 1491 | according to the squared quark charges.</li> |
---|
| 1492 | |
---|
| 1493 | <li>Changes in <code>FragmentationSystems</code> and |
---|
| 1494 | <code>StringFragmentation</code> to reject systems with three or more |
---|
| 1495 | interconnected junctions. This may happen in baryon-number-violating |
---|
| 1496 | scenarios in pp collisions, if both of the beam baryon junctions are |
---|
| 1497 | resolved and get connected via an antijunction created by a |
---|
| 1498 | hard-process BNV vertex. In principle, this could be addressed by an |
---|
| 1499 | extension of the existing junction fragmentation framework. However, |
---|
| 1500 | since it happens rarely, for the time being an error message is printed |
---|
| 1501 | and the fragmentation restarted. |
---|
| 1502 | </li> |
---|
| 1503 | |
---|
| 1504 | <li>Change in <code>Event::copy</code> to safeguard against attempting |
---|
| 1505 | to copy out-of-range entries. An attempt to copy a non-existing entry |
---|
| 1506 | will now return -1.</li> |
---|
| 1507 | |
---|
| 1508 | <li>Bug fix in the machinery for the user to force the setting of |
---|
| 1509 | tau polarization.</li> |
---|
| 1510 | |
---|
| 1511 | <li>Bug fix in the initial search for a maximum of the process |
---|
| 1512 | cross section (only affecting rare cases).</li> |
---|
| 1513 | |
---|
| 1514 | <li>Corrected angular decay distributions for two compositeness |
---|
| 1515 | processes, <code>Sigma2qq2qStarq</code> and |
---|
| 1516 | <code>Sigma2qqbar2lStarlbar</code>.</li> |
---|
| 1517 | |
---|
| 1518 | <li>Extra check in <code>HiddenValleyFragmentation</code> to make sure |
---|
| 1519 | that pointers which have not been assigned with <code>new</code> are not |
---|
| 1520 | deleted.</li> |
---|
| 1521 | |
---|
| 1522 | <li>Some further minor changes.</li> |
---|
| 1523 | |
---|
| 1524 | </ul> |
---|
| 1525 | </li> |
---|
| 1526 | |
---|
| 1527 | <li>8.160: 23 January 2012 |
---|
| 1528 | <ul> |
---|
| 1529 | |
---|
| 1530 | <li>The older term "multiple interactions" has been replaced by the |
---|
| 1531 | new standard "multiparton interactions" one, and correspondingly the |
---|
| 1532 | abbreviation MI by MPI. This affects everything: settings, class and |
---|
| 1533 | method names, documentation, etc. It therefore becomes necessary to |
---|
| 1534 | rewrite user code. However, so as to keep the immediate effort at a |
---|
| 1535 | reasonable level, the old settings names are kept as aliases. Thus |
---|
| 1536 | <code>PartonLevel:MI</code> and <code>PartonLevel:MPI</code> are |
---|
| 1537 | equivalent, and similarly <code>MultipleInteractions:pT0Ref</code> |
---|
| 1538 | and <code>MultipartonInteractions:pT0Ref</code>. Should you be using |
---|
| 1539 | methods such as <code>double Info::pTMI(int i)</code> you need to |
---|
| 1540 | edit the code, however. All the <code>example/main*</code> files |
---|
| 1541 | have been uopdated accordingly.</li> |
---|
| 1542 | |
---|
| 1543 | <li>A new option <code>Beams:frameType = 5</code> has been added |
---|
| 1544 | for the case where an external generator should provide LHA process |
---|
| 1545 | information. The new <code>Pythia::setLHAupPtr(...)</code> method |
---|
| 1546 | should then be used to link in this generator. The new switch |
---|
| 1547 | <code>Beams:newLHEFsameInit</code> can be used to tell that a new |
---|
| 1548 | LHEF should be used, but without the need for a new initialization. |
---|
| 1549 | With these two changes, all the different ways of initializing |
---|
| 1550 | can be covered by the <code>Pythia::init()</code> call with no |
---|
| 1551 | arguments. The various <code>init(...)</code>options with arguments |
---|
| 1552 | are deprecated and will be removed for PYTHIA 8.2.</li> |
---|
| 1553 | |
---|
| 1554 | <li> The <code>Pythia::stat()</code> method, with no arguments, |
---|
| 1555 | replaces <code>Pythia::statistics(...)</code>, although the latter |
---|
| 1556 | remains as a deprecated alternative.</li> |
---|
| 1557 | |
---|
| 1558 | <li>New settings <code>Init:...</code>, <code>Next:...</code>, |
---|
| 1559 | and <code>Stat:...</code> can be used to steer some details of |
---|
| 1560 | the operation of the <code>Pythia::init()</code>, |
---|
| 1561 | <code>Pythia::next()</code> and <code>Pythia::stat()</code>, |
---|
| 1562 | respectively. In particular it affects the amount of printout |
---|
| 1563 | at the various stages of operation. See |
---|
| 1564 | <?php $filepath = $_GET["filepath"]; |
---|
| 1565 | echo "<a href='MainProgramSettings.php?filepath=".$filepath."' target='page'>";?>here</a> for further details. |
---|
| 1566 | This change involves several code changes, but in documentation |
---|
| 1567 | rather than physics. Most of the <code>Main:...</code> settings |
---|
| 1568 | are deprecated as a consequence.</li> |
---|
| 1569 | |
---|
| 1570 | <li>The sample main programs in the <code>examples</code> subdirectory |
---|
| 1571 | have been updated. This includes a change to the new favoured |
---|
| 1572 | methods and settings outlined above, plus some update of the |
---|
| 1573 | physics contents. Some of the examples have been combined, |
---|
| 1574 | some others have been added (e.g. for R-hadroms), and as a consequence |
---|
| 1575 | some renumbering has been made. See the modified list of |
---|
| 1576 | <?php $filepath = $_GET["filepath"]; |
---|
| 1577 | echo "<a href='SampleMainPrograms.php?filepath=".$filepath."' target='page'>";?>sample main programs</a> for |
---|
| 1578 | the new status. In particular note that (the new) <code>main61.cc</code> |
---|
| 1579 | allows streamlined input and output in HepMC, like <code>main42.cc</code> |
---|
| 1580 | (previously <code>main32.cc</code>), but additionally links to LHAPDF. </li> |
---|
| 1581 | |
---|
| 1582 | <li>The <code>examples/configure</code> script has new optional argument |
---|
| 1583 | <code>--with-pythia8</code>. It can be used to set the new |
---|
| 1584 | <code>PYTHIA8LOCATION</code> environment variable, which then is used |
---|
| 1585 | in <code>examples/Makefile</code> to give the path to the PYTHIA |
---|
| 1586 | library. Thereby it becomes possible to relocate (parts of) the |
---|
| 1587 | <code>examples</code> directory and still obtain the correct path. |
---|
| 1588 | Thanks to Mikhail Kirsanov.</li> |
---|
| 1589 | |
---|
| 1590 | <li>Polarization information has been included as a new |
---|
| 1591 | <code>Particle</code> property, that can be set by |
---|
| 1592 | <code>void pol(double polIn)</code> and obtained by |
---|
| 1593 | <code>double pol()</code>. Default value is <code>9.</code>, |
---|
| 1594 | in agreement with the Les Houches standard. Event listings have |
---|
| 1595 | been expanded to optionally display this information. Currently |
---|
| 1596 | polarization is not used internally.</li> |
---|
| 1597 | |
---|
| 1598 | <li>The matrix element merging machinery has been modified as follows. |
---|
| 1599 | <br/>- Improved handling of the hard process, so that MadGraph5-produced |
---|
| 1600 | LHE files do not produce problems (sometimes, the choices of MG4 on what |
---|
| 1601 | to put into a LHEF have changed in MG5). |
---|
| 1602 | <br/>- Improved handling of colour for easier handling of states with |
---|
| 1603 | many quarks (the code has been tested for states with up to 5 |
---|
| 1604 | <i>q qbar</i> pairs and some gluons). |
---|
| 1605 | <br/>- Improved checking which clusterings are allowed. Now, clusterings |
---|
| 1606 | should immediately be rejected if they lead to unphysical states, |
---|
| 1607 | without the need to explicitly construct these states. This was needed |
---|
| 1608 | to get <i>t tbar</i> production, VBF and some simple SUSY processes |
---|
| 1609 | running with reasonable generality. |
---|
| 1610 | <br/>- Improved handling of incomplete histories. Now there is an |
---|
| 1611 | additional switch allowing code to try to swap some colours when fewer |
---|
| 1612 | clusterings than requested have been found. |
---|
| 1613 | </li> |
---|
| 1614 | |
---|
| 1615 | <li>Updates in the handling of graviton resonances in scenarios with |
---|
| 1616 | extra dimensions. |
---|
| 1617 | <br/>- Now all G decays have correct angular distribution, which was not |
---|
| 1618 | the case before for W/Z decays. |
---|
| 1619 | <br/>- Added the possibility for G to only couple to longitudinal |
---|
| 1620 | W/Z bosons, which affects both the width and angular distributions. |
---|
| 1621 | <br/>- Added decays to Higgs pairs, <i>G -> hh</i>. |
---|
| 1622 | </li> |
---|
| 1623 | |
---|
| 1624 | <li>Bug fix in the <code>findJunctions()</code> function in |
---|
| 1625 | <code>ProcessLevel.cc</code>. Changes introduced in version |
---|
| 1626 | 8.145 (to allow for junctions in baryon-number-violating |
---|
| 1627 | processes) did not correctly handle the remapping of color |
---|
| 1628 | tags that can be applied when adding beam remnants to events with |
---|
| 1629 | multiparton interactions. A simpler and more stable algorithm is |
---|
| 1630 | now applied for the simplest cases, with the more complex one only |
---|
| 1631 | invoked for cases such as BNV, which are normally considered before |
---|
| 1632 | remnants are added, hence avoiding this particular problem. Also some |
---|
| 1633 | other changes in the handling of junction, including a safeguard to |
---|
| 1634 | reject systems with three or more interconnected junctions.</li> |
---|
| 1635 | |
---|
| 1636 | <li>Bug fix and updates to the SLHA interface. Possibility of infinite |
---|
| 1637 | loop during <code>ProcessLevel::initSLHA</code> corrected. Modifications |
---|
| 1638 | to <code>SusyLesHouches</code> to allow interpretation of SLHA1 spectra |
---|
| 1639 | with R-parity violation. Rather than reject spectra that do not conform |
---|
| 1640 | fully to the SLHA2 standard for RPV, the interface will now first look |
---|
| 1641 | for SLHA1 mixing matrices and attempt to translate those into SLHA2 ones |
---|
| 1642 | if possible. In this case, warnings that the expected SLHA2 blocks were |
---|
| 1643 | not found will be printed. It is up to the user to check that the |
---|
| 1644 | derived SLHA2 information is correct. Corresponding additions to |
---|
| 1645 | <code>SusyCouplings.cc</code> to extract mixing-matrix information |
---|
| 1646 | from the relevant SLHA2 RPV blocks when RPV is switched on.</li> |
---|
| 1647 | |
---|
| 1648 | <li>Updated SLHA example <code>main24.cmnd</code> to use new example |
---|
| 1649 | spectrum, <code>cmssm.spc</code>, corresponding to CMSSM point |
---|
| 1650 | 10.1.1, obtained with SOFTSUSY 3.3.0. Thanks to B. Allanach for |
---|
| 1651 | providing the new spectrum file.</li> |
---|
| 1652 | |
---|
| 1653 | <li>A new <code>include/FastJet3.h</code> header file simplifies |
---|
| 1654 | interfacing of FastJet to Pythia. For details see documentation in |
---|
| 1655 | the file itself. Thanks to Gavin Salam for this contribution.</li> |
---|
| 1656 | |
---|
| 1657 | <li>The handling of diffraction has been made more flexible. |
---|
| 1658 | Specifically the "total" Pomeron-proton cross section can now be made |
---|
| 1659 | to depend on the mass of the diffractive system. This does not affect |
---|
| 1660 | the diffractive cross section in pp collisions, which is set separately, |
---|
| 1661 | but is used in the MPI machinery to affect the average number of |
---|
| 1662 | interactions per Pomeron-proton collision. Furthermore, the allowed |
---|
| 1663 | range for some parameters has been expanded. Thanks to Robert |
---|
| 1664 | Ciesielski.</li> |
---|
| 1665 | |
---|
| 1666 | <li>New method <code>Pythia::forceTimeShower(...)</code> can be used to |
---|
| 1667 | generate a single final-state cascade from a set of partons, without |
---|
| 1668 | any knowledge of prior history. This is mainly intended for toy studies. |
---|
| 1669 | The meaning of the <code>ProcessLevel:all</code> switch has been modified |
---|
| 1670 | so that this parton-level function is available, but not any others |
---|
| 1671 | at this level. |
---|
| 1672 | </li> |
---|
| 1673 | |
---|
| 1674 | <li>ATLAS tune A2 now included. Thanks to Deepak Kar for |
---|
| 1675 | providing it.</li> |
---|
| 1676 | |
---|
| 1677 | <li>Change in the handling of recoils of timelike showers in resonance |
---|
| 1678 | decays, in cases of coloured resonances such as <i>t -> b W</i>. In |
---|
| 1679 | the first step the <i>W</i> always acts as recoiler to the <i>b</i>, |
---|
| 1680 | but in subsequent step previously the <i>W</i> remained as recoiler to |
---|
| 1681 | one dipole, while now all QCD-radiating partons recoil against another |
---|
| 1682 | coloured parton. The old behaviour could give a (small) unphysical spike |
---|
| 1683 | of radition collinear with the colourless recoiler in the subsequent |
---|
| 1684 | emissions (while the pattern of the first was and remains correct). |
---|
| 1685 | The old behaviour can be recovered for checks, see |
---|
| 1686 | <code>TimeShower:recoilToColoured</code>. |
---|
| 1687 | Thanks to Yevgeny Kats for pointing out this issue (previously noted |
---|
| 1688 | for Pythia 6 by several persons). |
---|
| 1689 | </li> |
---|
| 1690 | |
---|
| 1691 | <li>Bug fixes for <code>rootexamples/Makefile</code> and restoration |
---|
| 1692 | of some deleted information in <code>rootexamples/README</code>. |
---|
| 1693 | Thanks to Axel Naumann and Bernhard Meirose.</li> |
---|
| 1694 | |
---|
| 1695 | <li>Bug fix, so that displaced vertices are possible in resonance |
---|
| 1696 | decay chains. Thanks to Daniel Blackburn and Andy Buckley for |
---|
| 1697 | pointing this out.</li> |
---|
| 1698 | |
---|
| 1699 | <li>Bug fix for <code>Info</code> counter 2.</li> |
---|
| 1700 | |
---|
| 1701 | <li>Bug fix so that sextet quarks now are read in correctly from |
---|
| 1702 | Les Houches Event files; previously the (anti)colours were set |
---|
| 1703 | to 0.</li> |
---|
| 1704 | |
---|
| 1705 | <li>Year updated to 2012 in copyright statements etc.</li> |
---|
| 1706 | |
---|
| 1707 | <li>Reformatting to reduce the number of code lines with more |
---|
| 1708 | than 79 characters.</li> |
---|
| 1709 | |
---|
| 1710 | <li><code>Pythia::initSLHA()</code> moved from <code>public</code> |
---|
| 1711 | to <code>private</code>. |
---|
| 1712 | </li> |
---|
| 1713 | |
---|
| 1714 | <li>Remove warning message when tau polarization is set by hand.</li> |
---|
| 1715 | |
---|
| 1716 | <li>Several minor changes to reduce the number of warnings issued |
---|
| 1717 | by the clang compiler. The origin of some warnings remains unclear |
---|
| 1718 | so those remain to track down (could also be compiler bugs; note that |
---|
| 1719 | we discuss warnings, not errors). Thanks to Randy MacLeod for bringing |
---|
| 1720 | this up.</li> |
---|
| 1721 | |
---|
| 1722 | <li>The worksheet has been updated to be in step with Pythia 8.160.</li> |
---|
| 1723 | |
---|
| 1724 | <li>Several other minor corrections in the code and documentation.</li> |
---|
| 1725 | |
---|
| 1726 | </ul> |
---|
| 1727 | </li> |
---|
| 1728 | |
---|
| 1729 | <li>8.162: 12 March 2012 |
---|
| 1730 | <ul> |
---|
| 1731 | |
---|
| 1732 | <li>A new option allows for several partons to share the recoil in |
---|
| 1733 | final-state radiation, see<?php $filepath = $_GET["filepath"]; |
---|
| 1734 | echo "<a href='TimelikeShowers.php?filepath=".$filepath."' target='page'>";?>Timelike |
---|
| 1735 | Showers</a>. It is mainly intended to be used in the context of |
---|
| 1736 | matching to matrix elements, and so only to be used in the first |
---|
| 1737 | few branchings.</li> |
---|
| 1738 | |
---|
| 1739 | <li>Several new processes for LED dijet production, see |
---|
| 1740 | <?php $filepath = $_GET["filepath"]; |
---|
| 1741 | echo "<a href='ExtraDimensionalProcesses.php?filepath=".$filepath."' target='page'>";?>Extra Dimensions</a>.</li> |
---|
| 1742 | |
---|
| 1743 | <li>Small update of the <code>Sigma2ffbar2LEDllbar</code> and |
---|
| 1744 | <code>Sigma2ffbar2LEDgammagamma</code> LED processes.</li> |
---|
| 1745 | |
---|
| 1746 | <li>New <code>Sigma2QCffbar2llbar</code> |
---|
| 1747 | <?php $filepath = $_GET["filepath"]; |
---|
| 1748 | echo "<a href='CompositenessProcesses.php?filepath=".$filepath."' target='page'>";?>contact interaction</a> |
---|
| 1749 | process.</li> |
---|
| 1750 | |
---|
| 1751 | <li>Inclusion of a new method in the |
---|
| 1752 | <?php $filepath = $_GET["filepath"]; |
---|
| 1753 | echo "<a href='MatrixElementMerging.php?filepath=".$filepath."' target='page'>";?>matrix-element merging</a> |
---|
| 1754 | framework to influence the construction of histories, e.g. to already |
---|
| 1755 | in the construction of histories disallow paths that fail the |
---|
| 1756 | <i>2 -> 2</i> cuts.</li> |
---|
| 1757 | |
---|
| 1758 | <li>Further minor updates of the matrix-element merging code, |
---|
| 1759 | mainly for improved clarity.</li> |
---|
| 1760 | |
---|
| 1761 | <li>Minor bug fix in the handling of beam and event information fed |
---|
| 1762 | in from an <code>LHAup</code> instance.</li> |
---|
| 1763 | |
---|
| 1764 | <li>Minor bug fix for potential crashes from uninitialized variables |
---|
| 1765 | for the merging machinery when merging is not used.</li> |
---|
| 1766 | |
---|
| 1767 | <li>Updated History class for matrix element merging, |
---|
| 1768 | also avoiding some compiler warnings.</li> |
---|
| 1769 | |
---|
| 1770 | <li>Bug fixes in the handling of correlated mass choices in resonance |
---|
| 1771 | decays, such as <i>H -> Z^*0 Z^*0</i>.</li> |
---|
| 1772 | |
---|
| 1773 | <li>Bug fix when the process-level execution is switched off, |
---|
| 1774 | where <code>Info::isResolved()</code> could be called before its |
---|
| 1775 | value was initialized. Thanks to Christian Pulvermacher |
---|
| 1776 | for finding this.</li> |
---|
| 1777 | |
---|
| 1778 | <li>Corrected matrix-element expression for mass selection in |
---|
| 1779 | <i>A^0 -> Z^*0 Z^*0</i> and <i>A^0 -> W^*+ W^*-</i>.</li> |
---|
| 1780 | |
---|
| 1781 | <li>SM Higgs mass updated to 125 GeV and default width and branching |
---|
| 1782 | ratios modified accordingly. Minor technical improvements of width |
---|
| 1783 | calculation.</li> |
---|
| 1784 | |
---|
| 1785 | <li>The usage of nested classes has been removed from |
---|
| 1786 | <code>SusyLesHouches</code>, since it could give compilation errors |
---|
| 1787 | on some platforms. The new class names begin with <code>LH</code> |
---|
| 1788 | and all classes have been put inside the <code>Pythia8</code> |
---|
| 1789 | namespace.</li> |
---|
| 1790 | |
---|
| 1791 | <li>Minor Makefile updates. Thanks to Mikhail Kirsanov.</li> |
---|
| 1792 | |
---|
| 1793 | <li>Minor changes to avoid some clang compiler warnings on the |
---|
| 1794 | Mac OS X platform.</li> |
---|
| 1795 | |
---|
| 1796 | </ul> |
---|
| 1797 | </li> |
---|
| 1798 | |
---|
| 1799 | <li>8.163: 27 March 2012 |
---|
| 1800 | <ul> |
---|
| 1801 | |
---|
| 1802 | <li>New methods in the |
---|
| 1803 | <?php $filepath = $_GET["filepath"]; |
---|
| 1804 | echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?><code>Info</code></a> class, |
---|
| 1805 | <code>id1pdf()</code>, <code>id2pdf()</code>, <code>x1pdf()</code> |
---|
| 1806 | and <code>x2pdf()</code>, to denote the partons for which parton |
---|
| 1807 | distribution values have been defined. Previously this was assumed |
---|
| 1808 | to agree with the incoming partons to the hard process, the same |
---|
| 1809 | methods without the <code>pdf</code> qualifier. However, now the |
---|
| 1810 | POWHEG approach offers a counterexample. Also the reading and |
---|
| 1811 | handling of Les Houches (and other) events, and the interface |
---|
| 1812 | to HepMC, has been modified accordingly. |
---|
| 1813 | </li> |
---|
| 1814 | |
---|
| 1815 | <li>The decay of Higgs and top resonances read in from Les Houches |
---|
| 1816 | Event files is now performed with angular correlations as for |
---|
| 1817 | internal processes. LHE files should normally contain all process-specific |
---|
| 1818 | resonance decay chains and, if not, decays are made isotropic. |
---|
| 1819 | The <i>H -> WW/ZZ -> f fbar f' fbar'</i> and |
---|
| 1820 | <i>t -> b W -> b f fbar</i> correlations are process-independent, |
---|
| 1821 | however, and thus can be handled internally. If part of the decay |
---|
| 1822 | chain has already been set, e.g. <i>H -> WW/Z></i> or <i>t -> b W</i>, |
---|
| 1823 | then the subsequent decays are still isotropic.</li> |
---|
| 1824 | |
---|
| 1825 | <li>Updated instructions how to link to HepMC, |
---|
| 1826 | in <code>README.HepMC</code>.</li> |
---|
| 1827 | |
---|
| 1828 | <li>Bug fix in the turn-on of resolved diffraction for low |
---|
| 1829 | CM energies. Thanks to Erwin Visser.</li> |
---|
| 1830 | |
---|
| 1831 | <li>Bug fix in the handling of string junctions at very high energies, |
---|
| 1832 | caused by numerical errors. Thanks to Erwin Visser.</li> |
---|
| 1833 | |
---|
| 1834 | <li>Some other small changes, mainly aesthetics.</li> |
---|
| 1835 | |
---|
| 1836 | </ul> |
---|
| 1837 | </li> |
---|
| 1838 | |
---|
| 1839 | <li>8.165: 8 May 2012 |
---|
| 1840 | <ul> |
---|
| 1841 | |
---|
| 1842 | <li>The MBR (Minimum Bias Rockefeller) model for single, double and |
---|
| 1843 | central diffraction [<a href="Bibliography.php" target="page">Cie12</a>] is included as new option |
---|
| 1844 | <?php $filepath = $_GET["filepath"]; |
---|
| 1845 | echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?><code>Diffraction:PomFlux = 5</code></a>. |
---|
| 1846 | It is specifically intended for <i>p p</i> and <i>pbar p</i> |
---|
| 1847 | interactions, and is currently the only option that also supports |
---|
| 1848 | central diffraction. Thus the basic machinery for Central Diffraction |
---|
| 1849 | (a.k.a. Double Pomeron Exchange) has now been implemented. |
---|
| 1850 | See <code>examples/main04.cc</code> for an example. |
---|
| 1851 | Thanks to Robert Ciesielski for contributing the new code. |
---|
| 1852 | </li> |
---|
| 1853 | |
---|
| 1854 | <li>For a <i>tau</i> lepton in an external process, by default the |
---|
| 1855 | SPINUP number in the Les Houches Accord now is interpreted as giving |
---|
| 1856 | the <i>tau</i> helicity, and is used for its decay.</li> |
---|
| 1857 | |
---|
| 1858 | <li>A <i>tau</i> coming from a <i>W</i> now defaults to being purely |
---|
| 1859 | lefthanded when neither of the existing matrix elements apply.</li> |
---|
| 1860 | |
---|
| 1861 | <li>Decay mode <i>t -> H+ b</i> included as an option.</li> |
---|
| 1862 | |
---|
| 1863 | <li>Four ATLAS tunes have been implemented as options for |
---|
| 1864 | <code>Tune:pp</code>: A2-minbias-mstw2008lo, AU2-cteq6l1, AU2-mstw2008lo, |
---|
| 1865 | and AU2-ct10. The new flag <code>Tune:preferLHAPDF</code> can be used |
---|
| 1866 | to switch between the LHAPDF and the internal implementation of a |
---|
| 1867 | PDF set, in cases where both are available.</li> |
---|
| 1868 | |
---|
| 1869 | <li>Reorder libraries in <code>examples/Makefile</code>, specifically |
---|
| 1870 | move <code>LIBGZIP</code> so that it is properly linked when used. |
---|
| 1871 | Thanks to Erik Schnetter.</li> |
---|
| 1872 | |
---|
| 1873 | <li>Minor modification so that LHAPDF can be used for PDFs in the hard |
---|
| 1874 | process, with one of the built-in PDFs for the rest, even if LHAPDF is |
---|
| 1875 | compiled so as to handle only one concurrent PDF set.</Li> |
---|
| 1876 | |
---|
| 1877 | <li>Bug fix, that <code>ParticleDecays:mixB = off</code> did not |
---|
| 1878 | switch off <i>B0 - B0bar</i> and <i>Bs0 - Bs0bar</i> mixing. |
---|
| 1879 | Thanks to James Catmore.</li> |
---|
| 1880 | |
---|
| 1881 | <li>Bug fix for the handling of gluon polarization of initial-state |
---|
| 1882 | radiation, where an anisotropic azimuthal distribution was inadvertently |
---|
| 1883 | generated in some <i>2 -> 1</i> processes. The update also includes |
---|
| 1884 | always setting the second daughter zero for the two partons coming in to |
---|
| 1885 | a hard <i>2 -> 1</i> process. Thanks to Antonio Policicchio.</li> |
---|
| 1886 | |
---|
| 1887 | <li>Bug fix, that the setting of the number of user hooks MPI steps did |
---|
| 1888 | not use <code>UserHooks::canVetoMPIStep()</code> properly.</li> |
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| 1889 | |
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| 1890 | <li>Some other small changes, mainly documentation and aesthetics.</li> |
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| 1891 | |
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| 1892 | </ul> |
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| 1893 | </li> |
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| 1894 | |
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| 1895 | <li>8.170: 21 September 2012 |
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| 1896 | <ul> |
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| 1897 | |
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| 1898 | <li>Streamline default behaviour and options for choice of GeV or MeV |
---|
| 1899 | for output to the HepMC event format, see |
---|
| 1900 | <?php $filepath = $_GET["filepath"]; |
---|
| 1901 | echo "<a href='HepMCInterface.php?filepath=".$filepath."' target='page'>";?>HepMC Interface</a>. |
---|
| 1902 | Also set the mass of HepMC particles explicitly, rather than having |
---|
| 1903 | it calculated implicitly. Thanks to James Monk and Andy Buckley.</li> |
---|
| 1904 | |
---|
| 1905 | <li>The <i>tau</i> decay machinery has been further augmented with |
---|
| 1906 | matrix elements and form factors for a variety of decay modes, such |
---|
| 1907 | that all modes with a branching ratio above 0.1% are fully modelled. |
---|
| 1908 | Several new classes and methods have been added to this end, |
---|
| 1909 | Also, a <i>tau</i> pair coming from a <i>Z^0</i> decay is now |
---|
| 1910 | handled by assuming the <i>Z^0</i> to be unpolarized when neither |
---|
| 1911 | of the existing matrix elements apply. Taus coming from B baryons are |
---|
| 1912 | handed as for B mesons.</li> |
---|
| 1913 | |
---|
| 1914 | <li>Flavour violating decays have been added to the squark, gluino, |
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| 1915 | neutralino and chargino decay tables.</li> |
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| 1916 | |
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| 1917 | <li>Extend the <code>UserHooks::subEvent(...)</code> method so that it |
---|
| 1918 | also works passably at the process level. Also new option for |
---|
| 1919 | <code>UserHooks::omitResonanceDecays(...)</code>.</li> |
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| 1920 | |
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| 1921 | <li>New methods <code>UserHooks::canVetoPartonLevelEarly()</code> |
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| 1922 | and <code>UserHooks::doVetoPartonLevelEarly( const Event&)</code> |
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| 1923 | are intended to be used the same way as the existing ones without |
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| 1924 | <code>Early</code> in their names, but allow veto right after |
---|
| 1925 | the ISR + FSR + MPI evolution, before beam remnants are added and |
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| 1926 | resonance decays are considered.</li> |
---|
| 1927 | |
---|
| 1928 | <li>Central diffraction now available for all |
---|
| 1929 | <code><?php $filepath = $_GET["filepath"]; |
---|
| 1930 | echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>PomFlux</a></code> |
---|
| 1931 | options, not only the MBR model. This has been constructed by analogy |
---|
| 1932 | with the respective assumptions made for single diffraction, but |
---|
| 1933 | includes some arbitrariness. Therefore the cross section is left |
---|
| 1934 | easily rescaleable and, for backwards compatibility with tunes |
---|
| 1935 | that does not contain it, easily possible to switch off, see |
---|
| 1936 | the <?php $filepath = $_GET["filepath"]; |
---|
| 1937 | echo "<a href='TotalCrossSections.php?filepath=".$filepath."' target='page'>";?>relevant section</a>. |
---|
| 1938 | </li> |
---|
| 1939 | |
---|
| 1940 | <li>Reading of ALPGEN parameter and event files has been added, |
---|
| 1941 | see <?php $filepath = $_GET["filepath"]; |
---|
| 1942 | echo "<a href='AlpgenAndMLM.php?filepath=".$filepath."' target='page'>";?>ALPGEN and MLM Merging</a>. |
---|
| 1943 | </li> |
---|
| 1944 | |
---|
| 1945 | <li>MLM matching has been added, as a first step for ALPGEN events, |
---|
| 1946 | see <?php $filepath = $_GET["filepath"]; |
---|
| 1947 | echo "<a href='AlpgenAndMLM.php?filepath=".$filepath."' target='page'>";?>ALPGEN and MLM Merging</a>. |
---|
| 1948 | </li> |
---|
| 1949 | |
---|
| 1950 | <li>The CKKW-L merging machinery has been upgraded in a number of respects. |
---|
| 1951 | <br/>- More thorough treatment of <code>pp>bb~e+e-veve~</code> with |
---|
| 1952 | additional <i>b</i>-jets. |
---|
| 1953 | <br/>- Corrected hard <i>mu_r</i> and <i>mu_f</i> choices for |
---|
| 1954 | dijet and promt photon. |
---|
| 1955 | <br/>- More ways to define a hard process, e.g. with the LEPTONS and |
---|
| 1956 | NEUTRINO tags. The merging will understand LHE files for mixed processes |
---|
| 1957 | (e.g. <i>W+</i> and <i>W-</i> production together). |
---|
| 1958 | <br/>- More merging scale definitions. |
---|
| 1959 | <br/>- More freedom to generate all possible histories. |
---|
| 1960 | <br/>- Internal check (and cut) on Les Houches events in |
---|
| 1961 | <code>Pythia::mergeProcess</code> if merging scale value of the events |
---|
| 1962 | is below the value given to Pythia by setting <code>Merging::TMS</code>. |
---|
| 1963 | </li> |
---|
| 1964 | |
---|
| 1965 | <li>It now works to have R-parity violating decays of R-hadrons, |
---|
| 1966 | i.e. baryon number violation in a vertex displaced from the primary |
---|
| 1967 | one.</li> |
---|
| 1968 | |
---|
| 1969 | <li>The documentation of diffractive processes by the |
---|
| 1970 | <code><?php $filepath = $_GET["filepath"]; |
---|
| 1971 | echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>Info</a></code> |
---|
| 1972 | methods has been expanded and corrected. This also include the |
---|
| 1973 | <code>list()</code> method.</li> |
---|
| 1974 | |
---|
| 1975 | <li>Particle masses and widths have been updated to agree with the |
---|
| 1976 | 2012 RPP values [<a href="Bibliography.php" target="page">Ber12</a>]. Thanks to Piotr Zyla for data file |
---|
| 1977 | and James Catmore for program to update the PYTHIA tables from this |
---|
| 1978 | input.</li> |
---|
| 1979 | |
---|
| 1980 | <li>New methods <code>jetAssignment</code> and <code>removeJet</code> |
---|
| 1981 | added to the <code>SlowJet</code> class.</li> |
---|
| 1982 | |
---|
| 1983 | <li>Introduce angular correlation in decay chain |
---|
| 1984 | <i>H -> gamma Z0 -> gamma f fbar</i>. Thanks to Tim Barklow and |
---|
| 1985 | Michael Peskin.</li> |
---|
| 1986 | |
---|
| 1987 | <li>Introduce simple way to bias the selection of <i>2 -> 2</i> |
---|
| 1988 | processes towards larger <i>pT</i> values, with a compensatingly |
---|
| 1989 | decreasing event weight, see |
---|
| 1990 | <?php $filepath = $_GET["filepath"]; |
---|
| 1991 | echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>Phase Space Cuts</a>. Only offers a |
---|
| 1992 | subset of the possibilities allowed by <code>UserHooks</code>, |
---|
| 1993 | but simpler to use. The <code>main08.cc</code> program has been |
---|
| 1994 | expanded to illustrate this possibility, and also expanded to |
---|
| 1995 | include low-<i>pT</i> subsamples.</li> |
---|
| 1996 | |
---|
| 1997 | <li>The two remaining non-NLO tunes from [<a href="Bibliography.php" target="page">ATL12</a>] are now |
---|
| 1998 | included.</li> |
---|
| 1999 | |
---|
| 2000 | <li>The <code><?php $filepath = $_GET["filepath"]; |
---|
| 2001 | echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>Info</a></code> methods |
---|
| 2002 | <code>nTried, nSelected, nAccepted, sigmaGen</code> and |
---|
| 2003 | <code>SigmaErr</code> now takes the code of an individual process |
---|
| 2004 | as an optional argument.</li> |
---|
| 2005 | |
---|
| 2006 | <li>It is now possible to generate resonance decays, followed by |
---|
| 2007 | showers and hadronization, without having them associated with any |
---|
| 2008 | specific process. This is part of an expanded |
---|
| 2009 | <?php $filepath = $_GET["filepath"]; |
---|
| 2010 | echo "<a href='HadronLevelStandalone.php?filepath=".$filepath."' target='page'>";?>Hadron-Level Standalone</a> |
---|
| 2011 | machinery, as before triggered by <code>ProcessLevel = off</code>, |
---|
| 2012 | but additionally requiring <code>Standalone:allowResDec = on</code>. |
---|
| 2013 | Input can either be directly into the <code>event</code> |
---|
| 2014 | event record or via a (simplified) Les Houches Event File.</li> |
---|
| 2015 | |
---|
| 2016 | <li>New <code>configure</code> script options <code>--installdir</code>, |
---|
| 2017 | <code>--prefix</code> and <code>--datadir</code> can be used to set the |
---|
| 2018 | location(s) to which the library, header and data directories |
---|
| 2019 | will be copied by a <code>make install</code> subsequent to the |
---|
| 2020 | <code>make</code>. Thanks to Mikhail Kirsanov.</li> |
---|
| 2021 | |
---|
| 2022 | <li>Fix charge in antiparticle name when particle read in from SLHA |
---|
| 2023 | file. Thanks to Johan Alwall.</li> |
---|
| 2024 | |
---|
| 2025 | <li>Pointers now only compared with == and != (not e.g. > 0), to avoid |
---|
| 2026 | warnings in gcc 4.7.</li> |
---|
| 2027 | |
---|
| 2028 | <li>New check that version number of the code matches that of the |
---|
| 2029 | XML files. If not, no events can be generated. Thanks to James Monk |
---|
| 2030 | for suggestion.</li> |
---|
| 2031 | |
---|
| 2032 | <li>New check that mother and daughter indices have been set to give |
---|
| 2033 | a consistent event history. Can be switched on/off with the new |
---|
| 2034 | <code>Check:history</code> flag.</li> |
---|
| 2035 | |
---|
| 2036 | <li>A new method <code>LHAup::newEventFile</code> has been added to |
---|
| 2037 | switch to reading in events from another LHE file without having to |
---|
| 2038 | reinitialize the whole class. Lower-level routines like |
---|
| 2039 | <code>openFile</code> and <code>closeFile</code> have been added to |
---|
| 2040 | handle correct order of operations also when an intermediate gzip |
---|
| 2041 | decompression step is involved.</li> |
---|
| 2042 | |
---|
| 2043 | <li><code>LHAup::eventLHEF()</code> can now be called with an optional |
---|
| 2044 | argument <code>false</code>, to make event files somewhat smaller by |
---|
| 2045 | reducing the amount of blanks.</li> |
---|
| 2046 | |
---|
| 2047 | <li>A new mode <code>Beams:nSkipLHEFatInit</code> introduced to |
---|
| 2048 | skip ahead the first few events in a Les Houches Event File (cf. the |
---|
| 2049 | <code>LHAup::skipEvent(nSkip)</code> method).</li> |
---|
| 2050 | |
---|
| 2051 | <li>Introduce a new pair of user hooks that can be used to reject |
---|
| 2052 | the sequence of hard-process resonance decays, without rejecting |
---|
| 2053 | the production of the primary resonances.</li> |
---|
| 2054 | |
---|
| 2055 | <li>The possibility of separate multiplicative prefactors to the |
---|
| 2056 | renormalization and factorization default <i>pT^2</i> scale has been |
---|
| 2057 | introduced for both timelike and spacelike showers.</li> |
---|
| 2058 | |
---|
| 2059 | <li>Bug fixes in history information for R-hadron production, which also |
---|
| 2060 | fixes HepMC conversion in this case.</li> |
---|
| 2061 | |
---|
| 2062 | <li>Bug corrected in <code>SigmaSusy.cc</code>, for chargino+neutralino |
---|
| 2063 | production. Indexing error for incoming quark states in the process |
---|
| 2064 | <code>Sigma2qqbar2charchi0</code>, resulted in incorrect CKM factors.</li> |
---|
| 2065 | |
---|
| 2066 | <li>Corrected a bug in <code>SusyLesHouches.cc</code>, for NMSSM spectra. |
---|
| 2067 | The unitarity check on the neutralino mixing matrix was faulty, leading |
---|
| 2068 | to erroneous messages about unitarity violations and SUSY being switched |
---|
| 2069 | off.</li> |
---|
| 2070 | |
---|
| 2071 | <li>Bug fixes in the handling of resolved and unresolved diffractive events. |
---|
| 2072 | Thanks to Robert Ciesielski for debug.</li> |
---|
| 2073 | |
---|
| 2074 | <li>Do not set up FSR dipoles for <i>2 -> 1</i> processes.</li> |
---|
| 2075 | |
---|
| 2076 | <li>Check that some channel open for resonance decays. Also further |
---|
| 2077 | check whether resonance decay treatment should be invoked.</li> |
---|
| 2078 | |
---|
| 2079 | <li>Bug fix in reading of particle names from SLHA input.</li> |
---|
| 2080 | |
---|
| 2081 | <li>Change mass, width and decay mode(s) of D*_s(10431). Thanks to |
---|
| 2082 | Michal Petran.</li> |
---|
| 2083 | |
---|
| 2084 | <li>Bug fix in leptoquark production (lepton sign in |
---|
| 2085 | <i>q g -> LQ l</i>).</li> |
---|
| 2086 | |
---|
| 2087 | <li>New argument added to <code>SpaceShower::reassignBeamPtrs</code> |
---|
| 2088 | for diffractive event processing, as already available for |
---|
| 2089 | <code>TimeShower</code>.</li> |
---|
| 2090 | |
---|
| 2091 | <li>Do not write warnings in <code>SpaceShower</code> for weights |
---|
| 2092 | above unity if the evolution scale is below 1 GeV^2.</li> |
---|
| 2093 | |
---|
| 2094 | <li>Add default values for member variables in some constructors, |
---|
| 2095 | and some related changes for <code>AlphaStrong</code> code.</li> |
---|
| 2096 | |
---|
| 2097 | <li>Warn if negative-energy parton in hadronization.</li> |
---|
| 2098 | |
---|
| 2099 | <li>The MPI <i>pT</i> values assumed in the beam remnant setting |
---|
| 2100 | of primordial <i>kT</i> and colour reconnection probability were |
---|
| 2101 | incorrect for diffractive events.</li> |
---|
| 2102 | |
---|
| 2103 | <li>The arrays with MPI information were not reset when parton or |
---|
| 2104 | hadron level fails and a new try is made. Only affected few events.</li> |
---|
| 2105 | |
---|
| 2106 | <li>MPI statistics can not yet be accumulated for diffractive events, |
---|
| 2107 | and therefore the relevant routine is no longer called.</li> |
---|
| 2108 | |
---|
| 2109 | <li>Bug fix in the double parton scattering suppression from |
---|
| 2110 | energy-momentum conservation.</li> |
---|
| 2111 | |
---|
| 2112 | <li>Outgoing proton masses were not set in the event record for |
---|
| 2113 | elastic scattering (but kinematics handling was correct).</li> |
---|
| 2114 | |
---|
| 2115 | <li>Bug fixes in the identification and documentation of junctions, |
---|
| 2116 | previously leading to some unnecessarily rejected events. Also |
---|
| 2117 | other improvements leading to fewer errors.</li> |
---|
| 2118 | |
---|
| 2119 | <li>Slightly increased values for FragmentationSystems:mJoin and |
---|
| 2120 | StringFragmentation::FACSTOPMASS to reduce failure rate, without |
---|
| 2121 | noticeably affecting event properties.</li> |
---|
| 2122 | |
---|
| 2123 | <li>The Les Houches cross section error is now taken into account |
---|
| 2124 | in the final Pythia error for strategies +-3. New methods |
---|
| 2125 | <code>LHAup::xSecSum()</code> and <code>LHAup::xErrSum()</code> |
---|
| 2126 | provide the necessary information. |
---|
| 2127 | </li> |
---|
| 2128 | |
---|
| 2129 | <li>When a tau pair comes from a massless photon, in dipole shower |
---|
| 2130 | evolution, for the decay description the mother photon is reassigned |
---|
| 2131 | to have the sum of the tau momenta.</li> |
---|
| 2132 | |
---|
| 2133 | <li>Minor change in initialization sequence for user hooks, |
---|
| 2134 | to allow for more flexibility.</li> |
---|
| 2135 | |
---|
| 2136 | <li>Do not print warnings when multiparton interaction weights are |
---|
| 2137 | only slightly above unity.</li> |
---|
| 2138 | |
---|
| 2139 | <li>Do not write warnings for three known particles that are so close |
---|
| 2140 | to threshold that widths are switched off to avoid trouble.</li> |
---|
| 2141 | |
---|
| 2142 | <li>Some minor typographical changes.</li> |
---|
| 2143 | |
---|
| 2144 | </ul> |
---|
| 2145 | </li> |
---|
| 2146 | </ul> |
---|
| 2147 | |
---|
| 2148 | </body> |
---|
| 2149 | </html> |
---|
| 2150 | |
---|
| 2151 | <!-- Copyright (C) 2012 Torbjorn Sjostrand --> |
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