1 | <chapter name="Update History"> |
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2 | |
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3 | <h2>Update History</h2> |
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4 | |
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5 | These update notes describe major updates relative to the baseline |
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6 | PYTHIA 8.100 version. However, they are less extensive than the |
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7 | corresponding update notes for PYTHIA 6. On the other hand, |
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8 | whereas the PYTHIA 6 manual is a static document, the PYTHIA 8 |
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9 | html/php pages are kept up to date for each subversion. |
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10 | |
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11 | <br/><br/> |
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12 | <b>Important note:</b>version 8.160 does introduce some elements of |
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13 | backwards incompatibility. Specifically, "multiple interactions", |
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14 | abbreviated MI, haa been renamed "multiparton interactions", MPI. |
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15 | This affects many parts of the code and documentation. Also some |
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16 | features are deprecated, although remaining until the end of the |
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17 | 8.1xx version series. |
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18 | |
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19 | |
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20 | <h3>Main news by version</h3> |
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21 | |
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22 | <ul> |
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23 | |
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24 | <li>8.105: 24 February 2008 |
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25 | <ul> |
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26 | |
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27 | <li>New option to initialize with arbitrary beam directions<br/> |
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28 | <code>pythia.init( idA, idB, pxA, pyA, pzA, pxB, pyB, pzB)</code></li> |
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29 | |
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30 | <li>Added capability to set <aloc href="BeamParameters">beam energy spread |
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31 | and beam vertex</aloc>. |
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32 | <br/> |
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33 | <b>Warning:</b> as a consequence, the old <code>Beams</code> group of |
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34 | settings has been moved to <code>BeamRemnants</code>, and |
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35 | <code>Beams</code> is now instead used for machine beam parameters. |
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36 | Therefore also some <code>Main</code> settings of this character have been |
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37 | regrouped, as follows: |
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38 | <table cellspacing="5"> |
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39 | <tr> <td>8.100 setting </td> <td>has been moved to </td> </tr> |
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40 | <tr> <td><code>Main:idA </code></td> |
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41 | <td><code>Beams:idA </code></td> </tr> |
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42 | <tr> <td><code>Main:idB </code></td> |
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43 | <td><code>Beams:idB </code></td> </tr> |
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44 | <tr> <td><code>Main:inCMframe </code></td> |
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45 | <td>(<code>Beams:frameType</code>) </td> </tr> |
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46 | <tr> <td><code>Main:eCM </code></td> |
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47 | <td><code>Beams:eCM </code></td> </tr> |
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48 | <tr> <td><code>Main:eA </code></td> |
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49 | <td><code>Beams:eA </code></td> </tr> |
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50 | <tr> <td><code>Main:eB </code></td> |
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51 | <td><code>Beams:eB </code></td> </tr> |
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52 | <tr> <td><code>Main:LHEF </code></td> |
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53 | <td><code>Beams:LHEF </code></td> </tr> |
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54 | </table></li> |
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55 | |
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56 | <li>The <code>forceHadronLevel()</code> method introduced for standalone |
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57 | hadronization.</li> |
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58 | |
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59 | <li><code>main15.cc</code> illustrated how either full hadronization or |
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60 | only decays of some particles can be looped over for the rest of the |
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61 | event retained.</li> |
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62 | |
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63 | <li>The <code>LHAevnt</code> and <code>LHAinit</code> classes have been |
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64 | joined into a new <code>LHAup</code> one, with new options that allow |
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65 | the writing of a Les Houches Event File.</li> |
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66 | |
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67 | <li>The <code>SusyLesHouches</code> class updated to handle |
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68 | SLHA version 2.</li> |
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69 | |
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70 | <li>Updated HepMC conversion routine.</li> |
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71 | |
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72 | <li>The static <code>ErrorMsg</code> class has been removed and |
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73 | its functionality moved into the non-static <code>Info</code> class, |
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74 | in the renamed Info file.</li> |
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75 | |
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76 | <li>Further reduction of the use of static, with related code changes. |
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77 | This should allow to have several almost independent <code>Pythia</code> |
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78 | instances. Some static classes still remain, however, notably for |
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79 | random number generation and particle properties.</li> |
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80 | |
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81 | <li>Limited capability to use two different <code>Pythia</code> instances |
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82 | for signal + pileup event generation, see <code>main19.cc</code> for an |
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83 | example.</li> |
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84 | |
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85 | <li>In the <code>Event</code> class the <code>=</code> and |
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86 | <code>=+</code> methods have been overloaded to allow the copying |
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87 | or appending of event records. Illustrated in <code>main19.cc</code>.</li> |
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88 | |
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89 | <li>The html and php page formatting improved with |
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90 | cascading style sheets.</li> |
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91 | |
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92 | <li>Several minor improvements and new options, including updated configure |
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93 | scripts.</li> |
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94 | |
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95 | </ul> |
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96 | </li> |
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97 | |
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98 | <li>8.108: 1 May 2008 |
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99 | <ul> |
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100 | |
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101 | <li>Correction in the event record, so that the beam particles in line |
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102 | 1 and 2 do not have any mother according to the <code>motherList</code> |
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103 | method. Previously the "system" entry in line 0 was counted as their |
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104 | mother, which gave rise to an unexpected extra vertex in the conversion |
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105 | to the HepMC format.</li> |
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106 | |
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107 | <li>Support for HepMC version 1 is removed, to simplify the code and |
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108 | reflect the evolution of the field.</li> |
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109 | |
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110 | <li>Status codes are stored in HepMC only as 1 for existing and 2 for |
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111 | decayed or fragmented particles (whereas previously the original PYTHIA |
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112 | codes were used for the latter).</li> |
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113 | |
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114 | <li>Parton densities are stored in HepMC as <ei>xf(x,Q^2)</ei> |
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115 | rather than the <ei>f(x,Q^2)</ei> used in (some) previous versions.</li> |
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116 | |
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117 | <li>The SusyLesHouches class has ben updated so that reading is fully |
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118 | compatible with the SLHA2 standard. </li> |
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119 | |
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120 | <li>Improved handling of the Higgs width, relevant for massive and thereby |
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121 | broad resonance shapes.</li> |
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122 | |
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123 | <li>The matrix elements for neutralino pair production have now been |
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124 | completed and checked.</li> |
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125 | |
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126 | <li>Ensure that <ei>alpha_strong</ei> does not blow up, by introducing |
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127 | a minimal scale somewhat above <ei>Lambda_3</ei> (roughly where |
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128 | <ei>alpha_strong = 10</ei>).</li> |
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129 | |
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130 | <li>New methods <code>isValence1()</code> and <code>isValence2()</code> |
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131 | in the <code>Info</code> class.</li> |
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132 | |
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133 | <li>Protection against division by zero in calculation of decay vertex |
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134 | (for zero-mass gluons with zero lifetime, where there should be no |
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135 | displacement).</li> |
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136 | |
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137 | <li>A new compilation option <code>-Wshadow</code> is introduced and |
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138 | code is rewritten at all places where this option gave warnings.</li> |
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139 | |
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140 | <li>Minor library correction to allow compilation with gcc 4.3.0.</li> |
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141 | |
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142 | </ul> |
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143 | </li> |
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144 | |
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145 | <li>8.114: 22 October 2008 |
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146 | <ul> |
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147 | |
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148 | <li>New rescattering description operational (but still experimental) |
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149 | for the case that FSR is not interleaved, but saved until after MPI, |
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150 | ISR and beam remnants have been handled. This involves much new code |
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151 | in several classes.</li> |
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152 | |
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153 | <li>A new class <code>PartonSystems</code> is introduced to |
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154 | keep track of which partons in the event record belong to which |
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155 | subcollision system, plus some further information on each subsystem. |
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156 | It takes over functionality previously found as part of the |
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157 | <code>Event</code> class, but leaves room for future growth.</li> |
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158 | |
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159 | <li>Add optional model, wherein an increased <ei>pT0</ei> turnoff scale |
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160 | for MPI and ISR is used for above-average active events, i.e. events that |
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161 | already have several MPI's or ISR emissions.</li> |
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162 | |
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163 | <li>Freeze GRV 94L distribution at small <ei>Q^2</ei> to avoid blowup.</li> |
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164 | |
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165 | <li>The <code>pythia.readFile(...)</code> method can now alternatively take |
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166 | an <code>istream</code> as argument instead of a <code>filename</code>.</li> |
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167 | |
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168 | <li>Minor bug correction in <code>PartonLevel.cc</code>; the bug could |
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169 | (rarely) give a segmentation fault.</li> |
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170 | |
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171 | </ul> |
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172 | </li> |
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173 | |
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174 | <li>8.120: 10 March 2009 |
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175 | <ul> |
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176 | |
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177 | <li>New rescattering description further developed, but not yet |
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178 | recommended for normal usage.</li> |
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179 | |
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180 | <li>Include new processes for Large Extra Dimensions and Unparticles, |
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181 | contributed by Stefan Ask. New test program <code>main28.cc</code> |
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182 | illustrates.</li> |
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183 | |
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184 | <li>Include further SUSY processes: neutralino-chargino and |
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185 | chargino-chargino pairs. The processes should be valid also |
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186 | in the case of non-minimal flavour violation and/or CP violation. |
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187 | Expanded machinery to keep track of SUSY parameters.</li> |
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188 | |
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189 | <li>Include backwards evolution of incoming photon as part of the |
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190 | <code>SpaceShower</code> initial-state radiation description. This |
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191 | allows you to simulate hard collisions where one of the incoming |
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192 | partons is a photon. New test program <code>main43.cc</code> |
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193 | illustrates.</li> |
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194 | |
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195 | <li>Allow separate mass and transverse momentum cuts when two hard |
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196 | subprocesses are generated in the same event.</li> |
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197 | |
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198 | <li>The default value for the border between short- and long-lived |
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199 | paticles has been changed from 1 mm to 10 mm, to better conform with |
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200 | LHC standards, see <aloc href="ParticleDecays">here</aloc>. |
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201 | The default is still to let all unstable particles decay.</li> |
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202 | |
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203 | <li>New ISR matrix-element correction to <ei>f -> f gamma</ei> |
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204 | in single <ei>W</ei> production.</li> |
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205 | |
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206 | <li>New method <code>Event::statusHepMC</code> returns the status |
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207 | code according to the HepMC conventions agreed in February 2009. |
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208 | The interface to HepMC now writes out status according to this |
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209 | convention.</li> |
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210 | |
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211 | <li>Add capability to link to FastJet, with expanded configure script |
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212 | and Makefile, and with <code>main61.cc</code> as new example.</li> |
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213 | |
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214 | <li>Update of <code>Makefile.msc</code>, with added support for latest |
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215 | Visual C++ Express edition and use of regexp to check nmake version.</li> |
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216 | |
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217 | <li>Update of <code>LHAFortran.h</code> and |
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218 | <code>Pythia6Interface.h</code>, to make the interface to Fortran |
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219 | routines work also under Windows. (Thanks to Anton Karneyeu.) |
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220 | |
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221 | <li>Updated and expanded worksheet.</li> |
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222 | |
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223 | <li>The manual pages in the <code>xmldoc</code> directory, and thereby |
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224 | also those of the <code>htmldoc</code> and <code>phpdoc</code> |
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225 | directories, have been significantly updated and expanded. In particular, |
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226 | in many places the class of each method is explicitly shown, as well as |
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227 | the type of the return value and of the arguments. This upgrade is not |
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228 | yet completed, but already covers the more relevant sections. </li> |
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229 | |
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230 | <li>The unary minus operator in the <code>Vec4()</code> returns a |
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231 | reference to a four-vector with all components negated, but leaves |
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232 | the original four-vector unchanged. Previously the four-vector itself |
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233 | was flipped.</li> |
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234 | |
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235 | <li>The <code>pPlus()</code> and <code>pMinus()</code> methods of a |
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236 | four-vector and an event-record particle are renamed <code>pPos()</code> |
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237 | and <code>pNeg()</code>, respectively.</li> |
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238 | |
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239 | <li>Include a further loop in <code>ProcessLevel</code>, so that a new |
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240 | process is generated in case of failures of a less severe nature.</li> |
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241 | |
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242 | <li>Introduce warning message for unexpected <code>meMode</code> in |
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243 | <code>ResonanceWidths</code>.</li> |
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244 | |
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245 | <li>Les Houches event reading framework has been rearranged for |
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246 | more flexibility. Some bugs corrected. Specifically, when scale |
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247 | is not set (<code>scale = -1.</code> in the Les Houches standard), |
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248 | PYTHIA did not attempt to set this scale itself, which typically |
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249 | lead to there not being any ISR or FSR. Now the |
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250 | <aloc href="CouplingsAndScales">rules for normal |
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251 | 1-, 2- and 3-body final states</aloc> are applied, with a trivial |
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252 | extension of the 3-body rules for higher multiplicities.</li> |
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253 | |
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254 | <li>Correct bug in the handling of parton densities, whereby it was |
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255 | not possible to switch to a new set, once a first initialization |
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256 | had been done.</li> |
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257 | |
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258 | <li>Correct bugs when several <code>Pythia::init</code> initialization |
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259 | calls are made in the same run, specifically in the case that pointers |
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260 | to external processes have been handed in. |
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261 | |
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262 | <li>Changes in <code>main03.cmnd</code> and <code>main04.cmnd</code> |
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263 | so that some nonstandard options are commented ou rather than active. |
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264 | Related comments inserted also in some other <code>.cmnd</code> files, |
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265 | but there without any change in program execution.</li> |
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266 | |
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267 | <li>A few further minor bug fixes.</li> |
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268 | |
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269 | <li>Update year to 2009.</li> |
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270 | |
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271 | </ul> |
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272 | </li> |
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273 | |
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274 | <li>8.125: 16 June 2009 |
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275 | <ul> |
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276 | |
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277 | <li>Hadronization and timlike-shower parameter default values updated |
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278 | according to a tune to LEP1 data by Hendrik Hoeth, using the |
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279 | Rivet + Professor framework.</li> |
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280 | |
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281 | <li>Many further SUSY production processes. SLHA readin expanded to cover |
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282 | also masses and decay modes. Example <code>main22.cc</code> updated, while |
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283 | <code>main33.cc</code> now superfluous and removed. </li> |
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284 | |
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285 | <li>Also further processes for extra dimensions.</li> |
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286 | |
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287 | <li>Stefan Ask joins as coauthor.</li> |
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288 | |
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289 | <li>The <code>TimeShower::shower(...)</code> method has gained |
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290 | a new argument, that forces the shower evolution to stop after |
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291 | a given number of branchings. A new method |
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292 | <code>TimeShower::pTLastInShower()</code> permits the last evolution |
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293 | <ei>pT</ei> to be read out. These extensions can be useful |
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294 | for matching studies. |
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295 | </li> |
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296 | |
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297 | <li>New optional argument <code>isInterleaved</code> added to |
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298 | <code>TimeShower::branch(...)</code>. Is false by default, but |
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299 | true when called from the parton level for interleaved evolution |
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300 | of several parton systems, optionally also with ISR and MPI.</li> |
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301 | |
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302 | <li>New methods <code>UserHooks::canSetResonanceScale()</code> |
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303 | and <code>UserHooks:scaleResonance(...)</code> allows an optional |
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304 | user choice of the maximum shower scale in resonance decays.</li> |
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305 | |
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306 | <li>A new method <code>SpaceShower::doRestart()</code> has been |
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307 | added, to help distinguish cases when a |
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308 | <code>SpaceShower::branch(...)</code> failure forces a complete |
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309 | restart of the evolution from ones where only the intended |
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310 | current branching has been vetoed. |
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311 | |
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312 | <li>When multiparton interactions are initialized, it is now |
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313 | possible to reduce both <ei>pT0</ei> and <ei>pTmin</ei> |
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314 | if necessary to find a valid solution where |
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315 | <ei>sigma_jet > sigma_nondiffractive</ei>. Previously |
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316 | only the former would be reduced, which could lead to |
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317 | infinite loops if too large a <ei>pTmin</ei> was used. |
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318 | Thanks to Sami Kama for pointing out the problem. |
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319 | </li> |
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320 | |
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321 | <li>The rescattering machinery is now essentially completed, and can |
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322 | be used also by others than the authors. For now, however, it can only |
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323 | be recommended for dedicated studies, not e.g. for generic tunes. |
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324 | </li> |
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325 | |
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326 | <li>Timelike and spacelike showers, and beam remnant handling, |
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327 | are modified to handle rescattering partons. Specifically, a new machinery |
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328 | is introduced to trace the recoils from the combination of rescattering |
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329 | with showers and primordial <ei>kT</ei>. Can assign space- or timelike |
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330 | virtualities to intermediate particles to have energy and momentum |
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331 | conserved locally. This affects the <code>PartonLevel</code>, |
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332 | <code>MultipartonInteractions</code>, <code>TimeShower</code>, |
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333 | <code>SpaceShowe</code>r and <code>BeamRemnants</code> classes. |
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334 | Further details to appear in the upcoming article on rescattering. |
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335 | (Another change is a reversal to pre-8.114 order for non-interleaved FSR, |
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336 | wherein also FSR is treated before beam remnants are attached.) |
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337 | </li> |
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338 | |
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339 | <li>Four new status codes introduced, as part of the rescattering |
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340 | description: |
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341 | <br/>45 : incoming rescattered parton, with changed kinematics owing |
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342 | to ISR in the mother system (cf. status 34); |
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343 | <br/>46 : incoming copy of recoiler when this is a rescattered parton |
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344 | (cf. status 42); |
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345 | <br/>54 : copy of a recoiler, when in the initial state of a different |
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346 | system from the radiator; |
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347 | <br/>55 : copy of a recoiler, when in the final state of a different |
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348 | system from the radiator. |
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349 | </li> |
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350 | |
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351 | <li>New method <code>Info::tooLowPTmin()</code> can tell whether the |
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352 | <ei>pTmin</ei> scales for showers or multiparton interactions are too low. |
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353 | </li> |
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354 | |
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355 | <li>Pion beams allowed, both <ei>pi^+</ei>, <ei>pi^-</ei> and |
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356 | <ei>pi^0</ei>. New machinery for the latter, where the valence |
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357 | flavour content is chosen to be either <ei>d dbar</ei> or |
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358 | <ei>u ubar</ei> for each new event. One internal pion PDF |
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359 | implemented, with others from LHAPDF.</li> |
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360 | |
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361 | <li>Treatment of Pomeron-proton collisions begun.</li> |
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362 | |
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363 | <li>Phase-space handling of hard processes and multiparton interactions |
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364 | slightly expanded to better allow for harder PDF's than proton ones, |
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365 | e.g. for Pomerons.</li> |
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366 | |
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367 | <li>The program documentation has been expanded with an |
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368 | alphabetical index of all methods that are described on the |
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369 | webpages, see the <aloc href="ProgramMethods">Program Methods</aloc> |
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370 | page. Also other sections of the documentation have been |
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371 | updated and expanded, including the worksheet.</li> |
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372 | |
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373 | <li>Several <code>list</code> methods have been made |
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374 | <code>const</code>. For the listing of events two new methods |
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375 | have been added, <code>Event::list()</code> and |
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376 | <code>Event::list(bool showScaleAndVertex, |
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377 | bool showMothersAndDaughters = false)</code>, |
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378 | that correspond to special cases of the general method.</li> |
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379 | |
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380 | <li>A new method <code>Pythia::LHAeventSkip(int nSkip)</code> |
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381 | permits a skip-ahead of the reading of external Les Houches |
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382 | Events, without the necessity to generate the intervening |
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383 | <code>nSkip</code> events in full. Makes use of the new |
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384 | <code>LHAup::skipEvent(int nSkip)</code> method to perform |
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385 | the operations. Mainly intended for debug purposes. |
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386 | |
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387 | <li>The <code>ClusterJet</code> jet finder now saves the last |
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388 | five clustering scales. Also a minor bug fix. Thanks to Nils |
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389 | Lavesson for this contribution.</li> |
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390 | |
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391 | <li>The <code>Particle::m2()</code> method now returns a negative |
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392 | number when the stored mass <ei>m</ei> is negative, as used to |
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393 | indicate spacelike virtualities. Also the |
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394 | <code>Particle::eCalc()</code>, <code>Particle::mT()</code> and |
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395 | <code>Particle::mT2()</code> methods have been modified. |
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396 | </li> |
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397 | |
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398 | <li>The <code><<</code> method to print our a four-vector has |
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399 | been expanded with a fifth number, the invariant length, with a minus |
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400 | sign for spacelike vectors, and provided within brackets to allow |
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401 | a simple visual distinction.</li> |
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402 | |
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403 | <li>New methods <code>Rndm::dumpState(string fileName)</code> and |
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404 | <code>Rndm::readState(string fileName)</code> allows to write or |
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405 | read the state of the random number generator to or from a binary file. |
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406 | </li> |
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407 | |
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408 | <li>New method <code>double GammaReal(double x)</code> returns the |
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409 | value of the <ei>Gamma</ei> function for arbitrary real argument. |
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410 | Some cross sections for extra-dimensional processes rewritten to |
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411 | make use of it. |
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412 | </li> |
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413 | |
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414 | <li>New example program <code>main29.cc</code> shows how |
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415 | to set up a fictitious process of a heavy system decaying |
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416 | to two particles or partons, with decays traced to stable |
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417 | particles, as relevant for astroparticle applications.</li> |
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418 | |
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419 | <li>Main programs that illustrate the HepMC interface have |
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420 | been updated to use version 2.04, including units and excluding |
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421 | deprecated output formats.</li> |
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422 | |
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423 | <li>The <code>main32.cc</code> example extended also to handle |
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424 | Les Houches Event Files.</li> |
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425 | |
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426 | <li>The Makefile has been modified so that "make clean" only |
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427 | removes the current compilation and library fles, while |
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428 | "make distclean" gives a more extensive reset and cleanup. |
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429 | Thanks to Nils Lavesson for this contribution. Some other |
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430 | minor Makefile corrections.</li> |
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431 | |
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432 | <li>Several main programs that use the |
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433 | <code>Main:timesToShow</code> mode have been corrected so as |
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434 | not to crash if this is set to zero. Also some other cosmetics |
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435 | changes in main programs that do not affect the running.</li> |
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436 | |
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437 | <li>Bug correction, in that previously a veto with user hooks |
---|
438 | was not propagated from parton showers inside resonance decays. |
---|
439 | </li> |
---|
440 | |
---|
441 | <li>Minor bug fix in <code>TimeShower</code> for kinematics with |
---|
442 | unequal beam-particle masses.</li> |
---|
443 | |
---|
444 | <li>Bug fix so that <code>PartonLevel:MPI = off</code> also works for |
---|
445 | minimum-bias events.</li> |
---|
446 | |
---|
447 | <li>Minor bug fix in the impact-parameter selection of multiparton |
---|
448 | interactions. Thanks to Sami Kama for pointing it out.</li> |
---|
449 | |
---|
450 | <li>String fragmentation for junction topology protected against |
---|
451 | numerical instability in boost.</li> |
---|
452 | |
---|
453 | <li>Bug correction in the handling of particle decays to partons, |
---|
454 | where the scale of the partons was set before the partons had been |
---|
455 | added to some arrays, leading to indexation out of bounds. |
---|
456 | Thanks to Vladislav Burylov for discovering this bug. |
---|
457 | </li> |
---|
458 | |
---|
459 | <li>Bug correction in the handling of particles with inhibited decay, |
---|
460 | where the decay vertex would be too far displaced, which could lead to |
---|
461 | infinite loop. Thanks to Sami Kama for debugging this. </li> |
---|
462 | |
---|
463 | <li>Check to avoid infinite loop in matrix-element handling of |
---|
464 | two-body decays.</li> |
---|
465 | |
---|
466 | <li>Bug correction to avoid infinite loops in Dalitz decay treatment. |
---|
467 | Some changes in the decay handling logic to allow a new try when the |
---|
468 | decay of a particle fails.</li> |
---|
469 | |
---|
470 | <li>Minor correction, so the pointer to the <code>Info</code> class |
---|
471 | is set also for user-written classes derived from <code>LHAup</code>. |
---|
472 | </li> |
---|
473 | |
---|
474 | <li>Correction for typo in the matrix element of the |
---|
475 | <code>Sigma3ff2HchgchgfftWW</code> class, for doubly charged Higgs |
---|
476 | production. Thanks to Merlin Kole for spotting it.</li> |
---|
477 | |
---|
478 | <li>Updated colour bookkeeping in junction-antijunction annihilation |
---|
479 | avoids later problems in <code>Pythia::check()</code>. </li> |
---|
480 | |
---|
481 | <li>Minor updates of the <code>Makefile.msc</code> file to work with |
---|
482 | Visual Studio 2008. Thanks to David Bailey for these modifications.</li> |
---|
483 | |
---|
484 | <li>Ensure that <code>nInit</code> in the <code>BeamParticle</code> |
---|
485 | class is set also for unresolved lepton beams.</li> |
---|
486 | |
---|
487 | <li>The <code>VetoEvolution</code> class, derived from |
---|
488 | <code>UserHooks</code>, is obsolete and has been removed.</li> |
---|
489 | |
---|
490 | </ul> |
---|
491 | </li> |
---|
492 | |
---|
493 | <li>8.130: 15 September 2009 |
---|
494 | <ul> |
---|
495 | |
---|
496 | <li>New machinery that allows multiparton interactions inside diffractive |
---|
497 | systems. Also new optional Pomeron flux factors and Pomeron PDFs. |
---|
498 | New page on <aloc href="Diffraction">diffraction</aloc> added, where |
---|
499 | further details are collected. Still not tuned, so to be used with |
---|
500 | caution.</li> |
---|
501 | |
---|
502 | <li>Make Peter Skands' "Tune 1" parameters for ISR and MPI default. |
---|
503 | The older simpler tune is still available as an option, see |
---|
504 | <code><aloc href="Tunes">Tune:pp</aloc></code>. |
---|
505 | </li> |
---|
506 | |
---|
507 | <li>New possible choices for a second hard process: charmonium, |
---|
508 | bottomonium, top pair and single top.</li> |
---|
509 | |
---|
510 | <li>New code for pair production of generic colour-triplet scalar, |
---|
511 | fermion or vector. Largely written by Johan Bijnens, partly recycling |
---|
512 | existing code.</li> |
---|
513 | |
---|
514 | <li>Add user hooks possibility to veto event after a given number |
---|
515 | of multiparton interactions.</li> |
---|
516 | |
---|
517 | <li>Add instructions how PYTHIA 8 can be used from inside ROOT. |
---|
518 | Thanks to Andreas Morsch for providing the text and Rene Brun |
---|
519 | for a simple example.</li> |
---|
520 | |
---|
521 | <li>The <code>main21.cc</code> example extended with an option |
---|
522 | for a single-particle gun.</li> |
---|
523 | |
---|
524 | <li>Improvements and bug fixes in rescattering framework.</li> |
---|
525 | |
---|
526 | <li>New method <code>Hist::table(string fileName)</code> provides a |
---|
527 | more direct way to print a two-column table of histogram contents |
---|
528 | into a file than the current <code>Hist::table(ostream& os = cout)</code>. |
---|
529 | </li> |
---|
530 | |
---|
531 | <li>Modify reading of external files so that a line only consisting of |
---|
532 | control characters counts as empty, the same way as a line only consisting |
---|
533 | of blanks already did. This includes carriage return, tabs and a few more, |
---|
534 | the ones represented by <code>\n \t \v \b \r \f \a</code>. Applies to |
---|
535 | Les Houches Event files, settings files and particle data files. </li> |
---|
536 | |
---|
537 | <li>Fix it so that the read-in of a Les Houches Event File for the |
---|
538 | hardest process can be combined with the faciliy to select a specified |
---|
539 | second hard process.</li> |
---|
540 | |
---|
541 | <li>New empty base class method <code>LHAup::fileFound()</code> |
---|
542 | allows the derived class <code>LHAupLHEF</code> to signal more |
---|
543 | clearly that a failed initialization is caused by a failure to open |
---|
544 | the desired file. </li> |
---|
545 | |
---|
546 | <li>Check that a pointer to an <code>LHAup</code> object has been set |
---|
547 | in <code>Pythia::LHAeventList()</code> and |
---|
548 | <code>Pythia::LHAeventSkip(...)</code> calls.</li> |
---|
549 | |
---|
550 | <li>Updated configure and Makefile, e.g. to build shared libraries |
---|
551 | on Mac OS X.</li> |
---|
552 | |
---|
553 | <li>The options with a direct link to hard-process generation |
---|
554 | in PYTHIA 6 has been removed. It is hardly ever used but |
---|
555 | complicates the build structure. (Owing to its usefulness for some |
---|
556 | debug work, it was reinstated in a limited form in version 8.135. |
---|
557 | Thus <code>main51.cc</code> now contains the complete interface, |
---|
558 | previously in separate files, and commented-out lines in |
---|
559 | <code>examples/Makefile</code> suggest how PYTHIA 6 could be linked.) |
---|
560 | </li> |
---|
561 | |
---|
562 | <li>New argument to <code>Info::errorMsg(...)</code> allows to |
---|
563 | show all error messages of a specific kind rather than only the |
---|
564 | first one, e.g. for initialization.</li> |
---|
565 | |
---|
566 | <li>Correction in decay table of righthanded Majorana neutrinos. |
---|
567 | Thanks to Arnaud Ferrari and Vladimir Savinov.</li> |
---|
568 | |
---|
569 | <li>Correction in expressions in the manual for <ei>H^+-</ei> couplings |
---|
570 | to an <ei>h^0</ei>, <ei>H^0</ei> or <ei>A^0</ei> and a <ei>W^+-</ei>. |
---|
571 | Thanks to Rikard Enberg.</li> |
---|
572 | |
---|
573 | <li>Fix for accessing uninitialized memory, caused by accessing the |
---|
574 | daughters of the incoming beams before these daughters actually existed. |
---|
575 | Thanks to David Bailey and Sami Kama. |
---|
576 | </li> |
---|
577 | |
---|
578 | <li>Uninitialized photon PDF inside the proton could give crazy results |
---|
579 | for processes with incoming photons. Thanks to Adam Davison.</li> |
---|
580 | |
---|
581 | <li>Bug fix such that finite lifetimes can be set also for particles |
---|
582 | produced in the hard process. To exemplify, the bug affected |
---|
583 | <ei>tau</ei> leptons produced in <ei>Z^0</ei> and <ei>W^+-</ei> |
---|
584 | decays. Thanks to Troels Petersen.</li> |
---|
585 | |
---|
586 | <li>Bug fix in <code>TimeShower</code>, that <code>beamOffset</code> |
---|
587 | could remain uninitialized. Thanks to Sami Kama.</li> |
---|
588 | |
---|
589 | <li>Minor correction to resonance decays: fail if the allowed mass |
---|
590 | range of a Breit-Wigner resonance is a small fraction of the total |
---|
591 | area under the resonance curve.</li> |
---|
592 | |
---|
593 | <li>Correction when all three valence quarks were kicked out from a |
---|
594 | proton and could give false messages that beam momentum had been |
---|
595 | used up.</li> |
---|
596 | |
---|
597 | <li>Clarify status codes needed for hadron-level standalone runs in |
---|
598 | order to avoid error messages, and modify the <code>main21.cc</code> |
---|
599 | example accordingly. </li> |
---|
600 | |
---|
601 | <li>Minor corrections in the processes for extra dimensions.</li> |
---|
602 | |
---|
603 | <li>Some other minor additions to existing facilities |
---|
604 | and minor bug fixes.</li> |
---|
605 | |
---|
606 | </ul> |
---|
607 | </li> |
---|
608 | |
---|
609 | <li>8.135: 10 January 2010 |
---|
610 | <ul> |
---|
611 | |
---|
612 | <li>All usage of static member methods inside Pythia8 has now been |
---|
613 | eliminated. This simplifies for you to have several simultaneous |
---|
614 | <code>Pythia</code> instances that are run with different conditions. |
---|
615 | The three main classes affected by this are the <code>Settings</code> |
---|
616 | and <code>ParticleData</code> databases and the <code>Rndm</code> |
---|
617 | random-number generator. You can no longer address the methods of these |
---|
618 | classes directly, but have to address them via the <code>settings</code>, |
---|
619 | <code>particleData</code> and <code>rndm</code> instances in the |
---|
620 | respective <code>Pythia</code> object. Also some other smaller pieces |
---|
621 | of code are affected, e.g. Standard Model and SUSY couplings |
---|
622 | (the latter in new files). |
---|
623 | <note>Note 1</note>: The documentation has been updated accordingly |
---|
624 | on these webpages, but the "A Brief Introduction to PYTHIA 8.1" |
---|
625 | still refers to the old behaviour of version 8.100. |
---|
626 | <note>Note 2</note>: the interface to the external LHAPDF library remains |
---|
627 | static, since LHAPDF is written in Fortran and thus by definition |
---|
628 | static. |
---|
629 | <note>Note 3:</note> if you want to have momentum smearing in |
---|
630 | <code>CellJet</code> you now need to send in a pointer to a |
---|
631 | random-number generator. |
---|
632 | </li> |
---|
633 | |
---|
634 | <li>Ten new proton PDF sets are made available internally: |
---|
635 | MRST LO* (2007), MRST LO** (2008), MSTW 2008 LO (central member), |
---|
636 | MSTW 2008 NLO (central member), CTEQ6L, CTEQ6L1, CTEQ6.6 (NLO, |
---|
637 | central member), CT09MC1, CT09MC2, and CT09MCS, see |
---|
638 | <aloc href="PDFSelection">PDF Selection</aloc>. The Pomeron PDF data |
---|
639 | files have been renamed for consistency. Thanks to Tomas Kasemets |
---|
640 | for help with this <ref>Kas10</ref>. |
---|
641 | </li> |
---|
642 | |
---|
643 | <li>New parameters <code>TimeShower:pTmaxFudgeMPI</code> and |
---|
644 | <code>SpaceShower:pTmaxFudgeMPI</code> introduced, to give the same |
---|
645 | functionality for multiparton interactions that |
---|
646 | <code>TimeShower:pTmaxFudge</code> and <code>SpaceShower:pTmaxFudge</code> |
---|
647 | do for the hardest.</li> |
---|
648 | |
---|
649 | <li>A few extensions of the <code>UserHooks</code> framework. |
---|
650 | New methods <code>UserHooks:canVetoISREmission()</code> and |
---|
651 | <code>UserHooks::doVetoISREmission(...)</code> allows the latest |
---|
652 | initial-state emission to be studied before being finalized, |
---|
653 | with the possibility to veto it. |
---|
654 | Similarly <code>Userhooks:canVetoFSREmission()</code> and |
---|
655 | <code>UserHooks::doVetoFSREmission(...)</code> can be used to |
---|
656 | veto the latest final-state emission.</li> |
---|
657 | |
---|
658 | <li>A number of loop counters have been introduced in the |
---|
659 | <code>Info</code> class, that offers some further information on |
---|
660 | the progress of the event generation, for use e.g. in conjunction |
---|
661 | with the <code>UserHooks</code> facility.</li> |
---|
662 | |
---|
663 | <li>The <code>Pythia::initTunes(...)</code> method is made public, so that |
---|
664 | it can be called before the normal call from <code>Pythia::init(...)</code>. |
---|
665 | That way it is possible to start out from a given tune and change a few |
---|
666 | of the parameters. |
---|
667 | </li> |
---|
668 | |
---|
669 | <li>Bug corrected in <code>LHAFortran.h</code> for hard-process input |
---|
670 | from Fortran commonblock. This did not work properly when the input |
---|
671 | was used in combination with a second hard process generated internally. |
---|
672 | Thanks to Mikhail Kirsanov and Roberto Chierici. |
---|
673 | |
---|
674 | <li>Insertion of missing initialization of <code>isInit</code> in the |
---|
675 | <code>Settings</code> and <code>ParticleData</code> constructors, and |
---|
676 | <code>nInit</code> for <code>BeamParticle</code>. |
---|
677 | Thanks to Leif Lönnblad.</li> |
---|
678 | |
---|
679 | <li>Updated <code>Makefile.msc</code> for Windows users.</li> |
---|
680 | |
---|
681 | <li>Fix of some non-optimal use of booleans, that give warnings on |
---|
682 | a Windows compiler. Thanks to Anton Karneyeu.</li> |
---|
683 | |
---|
684 | <li>New options for the <aloc href="SUSYLesHouchesAccord"> |
---|
685 | SUSY Les Houches Accord</aloc> such that, by default, |
---|
686 | particle and decay data are not overwritten for known Standard Model |
---|
687 | particles (including <ei>Z^0</ei>, <ei>W^+-</ei> and <ei>t</ei>, |
---|
688 | but excluding the Higgs).</li> |
---|
689 | |
---|
690 | <li>Bug fix in <code>SusyLesHouches</code>, where the reading of SLHA |
---|
691 | information embedded in an LHEF would not stop at the end of the header |
---|
692 | section.</li> |
---|
693 | |
---|
694 | <li>Bug correction for undefined secondary widths where decay products |
---|
695 | together are heavier than the mother. Also unit default secondary width |
---|
696 | values in the <code>DecayChannel</code> constructor.</li> |
---|
697 | |
---|
698 | <li>Documentation updated, including change of current year to 2010.</li> |
---|
699 | |
---|
700 | </ul> |
---|
701 | </li> |
---|
702 | |
---|
703 | <li>8.140: 16 July 2010 |
---|
704 | <ul> |
---|
705 | |
---|
706 | <li>Four new draft <aloc href="Tunes">tunes</aloc> available.</li> |
---|
707 | |
---|
708 | <li>Introduction of a new scenario for production of Hidden-Valley |
---|
709 | particles, and interleaved showering in the QCD and HV sectors, see |
---|
710 | the new <aloc href="HiddenValleyProcesses">Hidden Valleys</aloc> |
---|
711 | description. A longer physics writeup is available <ref>Car10</ref>. |
---|
712 | </li> |
---|
713 | |
---|
714 | <li>Implementation of <ei>2 -> 3</ei> phase space selection intended |
---|
715 | for QCD processes with massless partons. A new set of matching |
---|
716 | <aloc href="PhaseSpaceCuts">phase space cut parameters</aloc>. |
---|
717 | The <aloc href="QCDProcesses">ten different QCD <ei>2 -> 3</ei> |
---|
718 | processes</aloc> have been implemented making use of this new |
---|
719 | possibility, so far without a complete handling of possible colour |
---|
720 | flows, however.</li> |
---|
721 | |
---|
722 | <li>New processes have been added for |
---|
723 | <aloc href="CompositenessProcesses">contact interactions</aloc> in |
---|
724 | <ei>q q -> q q</ei> and <ei>q qbar -> q qbar</ei> scattering.</li> |
---|
725 | |
---|
726 | <li>A process has been added for TeV^-1 Sized |
---|
727 | <aloc href="ExtraDimensionalProcesses">Extra Dimensions</aloc>, which |
---|
728 | involves the electroweak KK gauge bosons, i.e. <ei>gamma_{KK}/Z_{KK}</ei>, |
---|
729 | in one TeV^-1 sized extra dimension; see <code>main30.cc</code> for |
---|
730 | an example. This scenario is described in <ref>Bel10</ref>. Thanks to |
---|
731 | Noam Hod and coworkers for contributing this code.</li> |
---|
732 | |
---|
733 | <li>In the Randall-Sundrum extra-dimensional scenario a new option has |
---|
734 | been added where SM fields can exist in the bulk rather than only on |
---|
735 | a brane. (Still under development.) Furthermore production of a |
---|
736 | Kaluza-Klein gluon state has been added, and the <code> main28.cc</code> |
---|
737 | test program extended.</li> |
---|
738 | |
---|
739 | <li>The scenario for monojets in Large Extra Dimensions has been expanded |
---|
740 | with an alternative for scalar graviton exchange instead of tensor one. |
---|
741 | </li> |
---|
742 | |
---|
743 | <li>New parameters for maximum scale of |
---|
744 | <aloc href="TimelikeShowers">timelike showers</aloc>, |
---|
745 | <code>TimeShower:pTmaxMatch</code>, and the dampening of hard radiation, |
---|
746 | <code>TimeShower:pTdampMatch</code> and <code>TimeShower:pTdampFudge</code>, |
---|
747 | by analogy with corresponding ones for spacelike showers. Also new method |
---|
748 | <code>TimeShower:limitPTmax(...)</code> to implement alternative procedures. |
---|
749 | For dipoles stretched to the beam the new switch |
---|
750 | <code>TimeShower:dampenBeamRecoil</code> allows to dampen radiation |
---|
751 | close to the beam direction, with a changed default behaviour.</li> |
---|
752 | |
---|
753 | <li>Azimuthal anisotropies from coherence arguments have been introduced |
---|
754 | for the spacelike parton showers, see <code>SpaceShower:phiIntAsym</code> |
---|
755 | and <code>SpaceShower:strengthIntAsym</code>. |
---|
756 | Also azimuthal anisotropies from gluon polarization have been introduced |
---|
757 | for the spacelike parton showers, see <code>SpaceShower:phiPolAsym</code>, |
---|
758 | and updated for timelike parton showers, see |
---|
759 | <code>TimeShower:phiPolAsym</code>.</li> |
---|
760 | |
---|
761 | <li>Improvements for the matching to POWHEG LHEF-style input illustrated |
---|
762 | by the new <code>main71.cc</code> example. See also <ref>Cor10</ref>.</li> |
---|
763 | |
---|
764 | <li>A set of new processes <ei>gamma gamma -> f fbar</ei>, with <ei>f</ei> |
---|
765 | quarks or leptons. Code for equivalent photon flux around an unresolved |
---|
766 | proton, with more to come. Thanks to Oystein Alvestad. |
---|
767 | </li> |
---|
768 | |
---|
769 | <li>A new option has been included to dampen the growth of the diffractive |
---|
770 | cross sections, see <aloc href="TotalCrossSections">Total Cross |
---|
771 | Sections</aloc>.</li> |
---|
772 | |
---|
773 | <li>A new method <code>virtual int SigmaProcess::idSChannel()</code> |
---|
774 | has been introduced. If overloaded to return a nonzero value then a |
---|
775 | <ei>2 -> n</ei> process will appear listed as a <ei>2 -> 1 -> n</ei> one. |
---|
776 | That is, an intermediate resonance with the requested identity will be |
---|
777 | inserted in the event record, even without appearing in the calculation |
---|
778 | of the matrix element proper. Thanks to Noam Hod for idea and code.</li> |
---|
779 | |
---|
780 | <li>A new method <code>SigmaProcess::convertM2()</code> has been introduced |
---|
781 | to optionally allow the <code>SigmaProcess::sigmaHat()</code> to return |
---|
782 | the squared matrix element rather than <ei>d(sigmaHat)/d(tHat)</ei> for |
---|
783 | <ei> 2 -> 2 </ei> processes. Furthermore kinematics is stored in the new |
---|
784 | <code>mME</code> and <code>pME</code> vectors for alternative cross |
---|
785 | section encodings.</li> |
---|
786 | |
---|
787 | <li>Different encoding of the <ei>f fbar -> Z W</ei> cross section, |
---|
788 | contributed by Merlin Kole, based on the cross section of |
---|
789 | Brown, Sahdev and Mikaelian. Gives a distinctly different cross section |
---|
790 | than the previous based on EHLQ (including their bug fix). |
---|
791 | In particular the problem with negative cross sections is now fixed.</li> |
---|
792 | |
---|
793 | <li>Minor updates: pass <code>xmlPath</code> to new MSTW and CTEQ PDFs; |
---|
794 | reset beams earlier to give cleaner documentation.</li> |
---|
795 | |
---|
796 | <li>The H1 Fit B LO parametrization to the Pomeron PDF has been included, |
---|
797 | and made new default for Pomerons. Thanks to Paul Newman for providing |
---|
798 | the data files.</li> |
---|
799 | |
---|
800 | <li>Three changes, in principle unrelated, but with the common objective |
---|
801 | to make the generation of a given event depend only on the values |
---|
802 | determined during the initialization stage and on the state of the |
---|
803 | random-number generator when the event is begun. The new default |
---|
804 | should ensure a reproducible stop-and-restart behaviour, convenient |
---|
805 | for debug purposes. Thanks to Michael Schmelling for stressing the |
---|
806 | desire for such a behaviour. |
---|
807 | <br/>(i) Introduction of a new option <code><aloc href="PhaseSpaceCuts"> |
---|
808 | PhaseSpace:increaseMaximum</aloc></code> that allows to switch between |
---|
809 | two strategies for handling the (hopefully rare) cases when the |
---|
810 | assumed maximum of the cross section function is exceeded during the |
---|
811 | event generation, with a changed default behaviour. In the old |
---|
812 | default the maximum could be increased if it was exceeded during the run, |
---|
813 | thereby introducing a memory of the previously generated events. |
---|
814 | <br/>(ii) Updated handling of random numbers with Gaussian distributions. |
---|
815 | The <code>gauss()</code> method now only generates one value at a time. |
---|
816 | Instead the new <code>gauss2()</code> method returns a pair of Gauss |
---|
817 | numbers, with related time savings. In the old approach one Gaussian |
---|
818 | number could be buffered, which introduced a memory. |
---|
819 | <br/>(iii) Minor bug fix in <code>MiniStringFragmentation</code>, where |
---|
820 | the popcorn baryon state was not reset for each new system, again |
---|
821 | giving a (flawed) memory.</li> |
---|
822 | |
---|
823 | <li>New directory <code>rootexample</code> with a simple code example |
---|
824 | how to use ROOT for histogramming in PYTHIA runs. See |
---|
825 | <aloc href="ROOTusage">ROOT Usage</aloc> for details. Thanks to Rene Brun. |
---|
826 | </li> |
---|
827 | |
---|
828 | <li>In the <code>HepMCinterface</code> the checks for unhadronized |
---|
829 | quarks and gluons are not performed if hadronization has been switched |
---|
830 | off.</li> |
---|
831 | |
---|
832 | <li>The <code>UserHooks::initPtr(...)</code> has been expanded so that |
---|
833 | pointers to more classes (beam particles, random number, couplings, etc.) |
---|
834 | are sent in, thereby increasing the scope of possible user-written code. |
---|
835 | Also, the <code>UserHooks::doVetoProcessLevel(Event& process)</code> |
---|
836 | now allows the <code>process</code> event record to be modified, |
---|
837 | even if it is not recommended. The new <code>Info::pTnow()</code> |
---|
838 | method returns the current <ei>pT</ei> scale of the combined MPI, ISR |
---|
839 | and FSR evolution, which can be useful for some user hooks decisions. |
---|
840 | </li> |
---|
841 | |
---|
842 | <li>Histograms of the <code>Hist</code> class can now be booked |
---|
843 | with up to 1000 bins, instead of the previous maximum 100. All bins |
---|
844 | can be written to file, but the line-printer style printing will join |
---|
845 | nearby bins so at most 100 are printed, as before. </li> |
---|
846 | |
---|
847 | <li>Updated <code>configure</code> and <code>Makefile</code> |
---|
848 | to allow 64-bit compilation and more options. Thanks to Mikhail Kirsanov, |
---|
849 | Rene Brun and Fons Rademakers.</li> |
---|
850 | |
---|
851 | <li>Bug fix in <code>ProcessLevel</code> for colour flow checks of |
---|
852 | junctions. Enables the decay of a neutralino to three quarks, e.g. |
---|
853 | Thanks to Nils-Erik Bomark.</li> |
---|
854 | |
---|
855 | <li>Bug fixes in <code>TimeShower</code>, where recoil partners in resonance |
---|
856 | decays of coloured particles, and recoil partners in QED dipoles when beams |
---|
857 | are not allowed to take a recoil, might not be correctly identified. </li> |
---|
858 | |
---|
859 | <li>Bug fix in <code>SpaceShower</code>: when used with a fixed |
---|
860 | <ei>alpha_strong</ei>, the threshold enhancement factor of |
---|
861 | <ei>g -> Q Qbar</ei> became undefined. Thanks to Stefan Prestel.</li> |
---|
862 | |
---|
863 | <li>Bug fix in initialization of resonance widths, where the |
---|
864 | <code>minWidth</code> parameter could be used uninitialized, |
---|
865 | occasionally resulting in strange initialization problems when |
---|
866 | kinematics needs to force at least one resonance to be off-shell.</li> |
---|
867 | |
---|
868 | <li>Minor updates of <code>main06.cc</code>, <code>main10.cc</code> |
---|
869 | and <code>main23.cc</code>.</li> |
---|
870 | |
---|
871 | <li>Bug fix in mother pointer of multiparton interactions in |
---|
872 | diffractive systems.</li> |
---|
873 | |
---|
874 | </ul> |
---|
875 | </li> |
---|
876 | |
---|
877 | <li>8.142: 15 August 2010 |
---|
878 | <ul> |
---|
879 | |
---|
880 | <li>The strategy for setting up tune values has been changed. |
---|
881 | Previously the <code>Tune:ee</code> and <code>Tune:pp</code> |
---|
882 | settings were only interpreted during the |
---|
883 | <code>Pythia::init(...)</code> stage. Now they are interpreted |
---|
884 | as soon as they are read. Specifically this means that it is |
---|
885 | possible to override any of the tune parameters by putting new |
---|
886 | commands below <code>Tune:ee</code> and <code>Tune:pp</code> |
---|
887 | in the <code>Pythia::readFile(...)</code> configuration file |
---|
888 | or in the list of <code>Pythia::readString(...)</code> commands. |
---|
889 | <br/>As a consequence of this change, the public |
---|
890 | <code>Pythia::initTunes(...)</code> method has been replaced by |
---|
891 | two private <code>Settings::initTuneEE(...)</code> and |
---|
892 | <code>Settings::initTunePP(...)</code> methods. |
---|
893 | <br/>If <code>Tune:ee</code> or <code>Tune:pp</code> are |
---|
894 | nonvanishing by default, then the corresponding tune variables |
---|
895 | are set also from the <code>Pythia</code> constructor, before any |
---|
896 | user changes are possible. Currently this is not relevant. |
---|
897 | </li> |
---|
898 | |
---|
899 | <li>Bug fix in the setup of the <code>Tune:pp = 5</code> and |
---|
900 | <code>= 6</code> options, which meant that diffractive cross |
---|
901 | sections were not reduced as advertised.</li> |
---|
902 | |
---|
903 | <li>The default value of <code>MultipartonInteractions:pT0Ref</code> |
---|
904 | has been slightly reduced so as to give a somewhat improved |
---|
905 | default description. It is not intended as a replacement for the |
---|
906 | specific tunes, however.</li> |
---|
907 | |
---|
908 | <li>Some comparisons between tunes and data, obtained with the |
---|
909 | Rivet package, have been posted on |
---|
910 | <a href="http://home.thep.lu.se/~richard/pythia81/"> |
---|
911 | http://home.thep.lu.se/~richard/pythia81/</a>. |
---|
912 | Further improvements can be expected from future Professor-based |
---|
913 | tunes. The current set of 2C, 2M, 3C and 3M "draft tunes" have |
---|
914 | deliberately been chosen different also to explore a range of |
---|
915 | possibilities. One not visible in the plots is the fraction |
---|
916 | of single and double diffractive events in the inelastic cross |
---|
917 | section. This is 32% in 2C and 2M, while it was reduced to |
---|
918 | 21% in 3C and 3M, and a recent ATLAS study (ATLAS-CONF-2010-048) |
---|
919 | would suggest 28+-4%.</li> |
---|
920 | |
---|
921 | <li>Minor changes in <code>TimeShower</code> and |
---|
922 | <code>SpaceShower</code>, as protection if the <ei>c</ei> or |
---|
923 | <ei>b</ei> masses are set small.</li> |
---|
924 | |
---|
925 | <li>Bug fix in <code>SpaceShower</code>, for case when <ei>phi</ei> |
---|
926 | angle selection is biased to take into account interference effects. |
---|
927 | </li> |
---|
928 | |
---|
929 | <li>The <code>SigmaProcess::convertM2()</code> method now has |
---|
930 | been implemented also for <ei>2 -> 1</ei> processes, so that it is |
---|
931 | possible to provide the squared matrix element instead of |
---|
932 | <ei>sigmaHat</ei> for semi-internal processes. A fixed-width |
---|
933 | Breit-Wigner is also inserted, since the matrix element is supposed |
---|
934 | not to include it.</li> |
---|
935 | |
---|
936 | <li>New method <code>SigmaProcess::setupForME()</code> does an |
---|
937 | extended conversion from the internal kinematics to an almost |
---|
938 | equivalent one, better adapted to the mass conventions of matrix-element |
---|
939 | caclulation programs, such as massive incoming <ei>b</ei> quarks. |
---|
940 | New flags allow to determine whether the <ei>c</ei>, <ei>b</ei>, |
---|
941 | <ei>mu</ei> and <ei>tau</ei> should be considered massless or not |
---|
942 | in the calculations.</li> |
---|
943 | |
---|
944 | <li>Two new friend methods <code>table</code> of the <code>Hist</code> |
---|
945 | class allow to print a table with three columns, the first for the |
---|
946 | (common!) <ei>x</ei> values and the other two for the respective |
---|
947 | histogram values. A new method <code>takeSqrt</code> for the square |
---|
948 | root of histogram bin contents. |
---|
949 | </li> |
---|
950 | |
---|
951 | </ul> |
---|
952 | </li> |
---|
953 | |
---|
954 | <li>8.145: 10 November 2010 |
---|
955 | <ul> |
---|
956 | |
---|
957 | <li><code>Couplings</code> is defined in <code>StandardModel.h</code> |
---|
958 | as a derived class of <code>coupSM</code> and has only one extra flag: |
---|
959 | <code>isSUSY</code> to check presence of extra couplings.Changed all |
---|
960 | pointers <code>CoupSM*</code> to <code>Couplings*</code> and removed |
---|
961 | explicit references to <code>CoupSUSY*</code>. The <code>coupSUSY</code> |
---|
962 | object is only initialised if SUSY couplings are present. The new pointer |
---|
963 | <code>couplingsPtr</code> points either to only SM couplings or SM+SUSY |
---|
964 | couplings based on SLHA data.</li> |
---|
965 | |
---|
966 | <li>New files <code>SusyResonanceWidths.h/cc</code> contains the |
---|
967 | <code>SusyResonanceWidths</code> class, which inherits from |
---|
968 | <code>ResonanceWidths</code> but typecasts the <code>couplingsPtr</code> |
---|
969 | to <code>(CoupSUSY*) coupSUSYPtr</code>. This is the base class for |
---|
970 | all SUSY resonances. It contains the <code>ResonanceSquark</code> class |
---|
971 | for all squark decays. A new flag <code>SLHA:useDecayTable</code> |
---|
972 | to check if internal widths should be overwritten by those read in |
---|
973 | via SLHA.</li> |
---|
974 | |
---|
975 | <li>Added new functionality to <code>SusyLesHouches</code> for read-in |
---|
976 | of generic user blocks in the SLHA format, along with methods to |
---|
977 | extract parameters from them with typecasting controlled by the user. |
---|
978 | Intended for use with user-written semi-internal processes.</li> |
---|
979 | |
---|
980 | <li>Added <code>Sigma1qq2antisquark</code> cross section.</li> |
---|
981 | |
---|
982 | <li>Some new flags and modes in the <code>SUSY</code> and |
---|
983 | <code>SLHA</code> series offer further functionality.</li> |
---|
984 | |
---|
985 | <li>Several further changes as a consequence of the upgrade of the SUSY |
---|
986 | machinery.</li> |
---|
987 | |
---|
988 | <li>Bug/typo fixes in rotation matrices for SUSY couplings and for the |
---|
989 | processes <code>qqbar2squarkantisquark</code>, |
---|
990 | <code>qq2squarksquark</code> and more.</li> |
---|
991 | |
---|
992 | <li>Improved handling of colour junctions. Added new example program |
---|
993 | <code>main72.cc</code>, to illustrate read-in of color junction |
---|
994 | structures via LHEF (<code>main72.lhe</code>). The example used is SUSY |
---|
995 | with RPV.</li> |
---|
996 | |
---|
997 | <li>New Tune 4C introduced as <code>Tune:pp = 5</code>. The more crude |
---|
998 | (non-)tunes 3C and 3M are removed.</li> |
---|
999 | |
---|
1000 | <li>New methods <code>Settings::getFlagMap(...)</code>, |
---|
1001 | <code>Settings::getModeMap(...)</code>, |
---|
1002 | <code>Settings::getParmMap(...)</code> and |
---|
1003 | <code>Settings::getWordMap(...)</code> allows to return a map of all |
---|
1004 | settings of the respective type that contain a specific string |
---|
1005 | in its name. |
---|
1006 | </li> |
---|
1007 | |
---|
1008 | <li>Improved description of excited <ei>g^*/KK-gluon^*</ei> production |
---|
1009 | in the <code>Sigma1qqbar2KKgluonStar</code> and |
---|
1010 | <code>ResonanceKKgluon</code> classes.</li> |
---|
1011 | |
---|
1012 | <li>Possibility added to let Hidden-Valley <ei>gamma_v</ei> have |
---|
1013 | a nonero mass and decay by mixing with the ordinary photon. |
---|
1014 | Still experimental.</li> |
---|
1015 | |
---|
1016 | <li>Minor bug fix in handling of three-body phase space.</li> |
---|
1017 | |
---|
1018 | <li>Minor correction in <code>Sigma2ffbar2TEVffbar</code> class.</li> |
---|
1019 | |
---|
1020 | <li>Bug fix for decays of <ei>W'</ei> to a pair of heavy fermions when |
---|
1021 | <ei>gV != gA</ei>. Thanks to M. Chizhov, see arXiv:0705.3944. </li> |
---|
1022 | |
---|
1023 | <li>Restore the older EHLQ-based encoding of the <ei>f fbar -> Z W</ei> |
---|
1024 | cross section, which was changed in version 8.140, since comparisons |
---|
1025 | with Madgraph gives much better agreement with it than with the |
---|
1026 | expression of Brown, Sahdev and Mikaelian.</li> |
---|
1027 | |
---|
1028 | <li>The <code>HepMCInterface</code> now also stores colour flow |
---|
1029 | information for coloured particles.</li> |
---|
1030 | |
---|
1031 | <li>Pointer to <code>Couplings</code> made available for particle |
---|
1032 | decays.</li> |
---|
1033 | |
---|
1034 | <li>Minor update in <code>main61.cc</code> for more elegant usage |
---|
1035 | of FastJet, as suggested by Gregory Soyez.</li> |
---|
1036 | |
---|
1037 | </ul> |
---|
1038 | </li> |
---|
1039 | |
---|
1040 | <li>8.150: 20 April 2011 |
---|
1041 | <ul> |
---|
1042 | |
---|
1043 | <li>Tune 4C is made default. It is based on first comparisons with |
---|
1044 | LHC data <ref>Cor10a</ref>, and has also been checked independently |
---|
1045 | <ref>Buc11</ref> to give reasonable agreement with many distributions. |
---|
1046 | </li> |
---|
1047 | |
---|
1048 | <li>The description of <ei>tau</ei> lepton decays has been significantly |
---|
1049 | enhanced, to include helicity information related to the production |
---|
1050 | process and hadronic currents fitted to data. A complete writeup is |
---|
1051 | in preparation <ref>Ilt11</ref>. A new flag is introduced to revert |
---|
1052 | to the old behaviour, for cross-checks, see |
---|
1053 | <aloc href="ParticleDecays">Particle Decays</aloc>. |
---|
1054 | The new tau decay machinery is on by default. |
---|
1055 | </li> |
---|
1056 | |
---|
1057 | <li>A new option <code>MultipartonInteractions:bProfile = 4</code> has |
---|
1058 | been introduced for the impact-parameter profile of protons in the |
---|
1059 | <aloc href="MultipartonInteractions">Multiparton Interactions</aloc> |
---|
1060 | framework, wherein low-<ei>x</ei> partons are spread over a larger area |
---|
1061 | than high-<ei>x</ei> ones, see <ref>Cor11</ref>. A new method |
---|
1062 | <code>Info::eMPI(i)</code> gives back the enhancement factor related to |
---|
1063 | the <code>i</code>'th interaction. The impact-parameter profile can now |
---|
1064 | be selected separately for <aloc href="Diffraction">diffraction</aloc>, |
---|
1065 | but without a <code>bProfile = 4</code> option. |
---|
1066 | </li> |
---|
1067 | |
---|
1068 | <li>The possibility of "hadronization" in the |
---|
1069 | <aloc href="HiddenValleyProcesses">Hidden Valley</aloc> sector |
---|
1070 | has been added as a new option <code>HiddenValley:fragment = on</code>. |
---|
1071 | This is based on a copy of the standard string fragmentation framework, |
---|
1072 | but with the option of a completely separate "flavour" sector, and |
---|
1073 | separately tunable longitudinal fragmentation functions and transverse |
---|
1074 | momenta. For now only a simple flavour scenario is provided, where |
---|
1075 | flavour-diagonal mesons can decay back into the normal visible sector |
---|
1076 | while off-diagonal ones remain hidden. A writeup of the model is in |
---|
1077 | preparation <ref>Car11</ref>. Also some further Hidden Valley options |
---|
1078 | have been added.</li> |
---|
1079 | |
---|
1080 | <li>Included possibility in <code>TimeShower</code> for QCD dipoles to |
---|
1081 | have an adjustible normalization factor, via the new |
---|
1082 | <code>bool isFlexible</code> and <code>double flexFactor</code> |
---|
1083 | properties of <code>class TimeDipoleEnd</code>. This flexibility is used |
---|
1084 | to treat radiation off colour topologies with epsilon tensors, in |
---|
1085 | particular colour junctions which have all their partons in the |
---|
1086 | final state. (An example is the BNV-SUSY decay ~chi0→uds.) For |
---|
1087 | such topologies, the new treatment in PYTHIA 8 is that a |
---|
1088 | half-strength dipole is spanned between all combinations of |
---|
1089 | final-state quarks. For junctions with an incoming (anti)colour line (such |
---|
1090 | as in the BNV-SUSY decay ~t*→cb), a full-strength dipole is |
---|
1091 | instead spanned between the two daughters, with no radiation from the |
---|
1092 | decaying object (in its CM). As will be described in a fortcoming |
---|
1093 | paper with N. Desai, this should give the |
---|
1094 | closest possible correspondence to the radiation patterns exhibited |
---|
1095 | by higher-order matrix elements for this type of process.</li> |
---|
1096 | |
---|
1097 | <li>Corrected harmless bugs in <code>ProcessLevel::findJunctions</code> |
---|
1098 | which caused junctions of types 3 and 4 (i.e., junctions with 1 |
---|
1099 | incoming color tag) to sometimes be incorrectly classified as types |
---|
1100 | 1 and 2 (with all color tags outgoing), respectively. |
---|
1101 | Since the parity (even/odd) of the junction kind was still correct, |
---|
1102 | however, this did not cause any problems at the hadronization |
---|
1103 | stage.</li> |
---|
1104 | |
---|
1105 | <li>The junction-finder in <code>ProcessLevel::findJunctions</code> |
---|
1106 | has been made more stable, and the following ordering of the color |
---|
1107 | tags returned by <code>Event::endColJunction(iJun, iLeg)</code> is |
---|
1108 | now enforced: for junction kinds 3 and 4 (one tag |
---|
1109 | incoming), <code>iLeg = 0</code> will return the |
---|
1110 | incoming tag, while for kinds 5 and 6 (two tags incoming), |
---|
1111 | <code>iLeg = 0</code> and <code>iLeg = 1</code> will return the |
---|
1112 | incoming tags. Apart from this ordering, the color tags are |
---|
1113 | ordered in ascending color tag number.</li> |
---|
1114 | |
---|
1115 | <li>Declarations of friend functions moved to sit outside the class |
---|
1116 | it befriends. Thanks to Axel Naumann for pointing out the incorrect |
---|
1117 | previous construction.</li> |
---|
1118 | |
---|
1119 | <li>The <code>rootexample</code> subdirectory becomes |
---|
1120 | <code>rootexamples</code> as the old example is split into two, |
---|
1121 | with improved documentation to clarify usage. Thanks to Axel Naumann |
---|
1122 | and Bernhard Meirose for the new code.</li> |
---|
1123 | |
---|
1124 | <li>In the Les Houches Event File machinery, input type has been |
---|
1125 | changed from <code>ifstream</code> to <code>istream</code> for more |
---|
1126 | flexibility.</li> |
---|
1127 | |
---|
1128 | <li>R-hadron handling is largely implemented, see the |
---|
1129 | <aloc href="RHadrons">R-hadrons</aloc> page, although some aspects |
---|
1130 | still need polishing. A new class <code>RHadrons</code> takes |
---|
1131 | care of the hadronization and decay. Particle data have been added |
---|
1132 | for R-hadrons containing a gluino, stop or sbottom, but could |
---|
1133 | alternatively be used for other long-lived coloured particles. |
---|
1134 | Thanks to Bernhard Meirose for support. |
---|
1135 | </li> |
---|
1136 | |
---|
1137 | <li>Calculations of SUSY decay widths included by |
---|
1138 | N. Desai, contained in the new source |
---|
1139 | files <code>SusyResonanceWidth.cc</code> |
---|
1140 | and </code>.h</code>. Validation and addition of more modes is still in |
---|
1141 | progress, so this implementation should be considered preliminary |
---|
1142 | for now. For a list of available modes, see |
---|
1143 | the <aloc href="SUSYProcesses">SUSY Processes</aloc> page. |
---|
1144 | </li> |
---|
1145 | |
---|
1146 | <li>A first implementation of the SLHA-based QNUMBERS interface for |
---|
1147 | defining new exotic particles has been |
---|
1148 | included. See <ref>Alw07</ref> and |
---|
1149 | the <aloc href="SUSYLesHouchesAccord">SUSY Les Houches Accord</aloc> |
---|
1150 | page. </li> |
---|
1151 | |
---|
1152 | <li>Read-in of LHEF events containing Baryon Number Violating vertices |
---|
1153 | has been included, using colour junctions, see |
---|
1154 | the <aloc href="EventRecord">Event Record</aloc> page. The advanced |
---|
1155 | shower model taking into account the full colour structure of such |
---|
1156 | events, developed by N. Desai and described above, |
---|
1157 | is turned on by default in such events. |
---|
1158 | Several test cases were used to |
---|
1159 | validate this implementation, but it is possible that problems could |
---|
1160 | still exist for some cases. Feedback is welcome. Thanks to |
---|
1161 | the MadGraph authors for providing several test cases.</li> |
---|
1162 | |
---|
1163 | <li>Some first steps taken to allow events containing colour sextets, |
---|
1164 | e.g., from semi-internal processes or LHEF interfaces, and/or from |
---|
1165 | SLHA <code>DECAY</code> tables. New |
---|
1166 | <code>colType</code> codes 3 and -3 are introduced to describe |
---|
1167 | sextets and antisextets, respectively. The state of the current |
---|
1168 | implementation is that hard processes containing such states can be |
---|
1169 | read in and decays generated (via <code>DECAY</code> tables). Parton |
---|
1170 | showers can be added, but the sextets themselves do not, as yet, |
---|
1171 | shower, and any undecayed sextets remaining at the hadronization |
---|
1172 | stage would lead to unpredictable problems if hadronization is |
---|
1173 | switched on. Thanks to J. Alwall for help with testing |
---|
1174 | this implementation. |
---|
1175 | </li> |
---|
1176 | |
---|
1177 | <li>The functionality of the SLHA SUSY/BSM interface (see |
---|
1178 | the <aloc href="SUSYLesHouches">SUSY Les Houches</aloc> page) has been |
---|
1179 | extended so that copies of all <code>BLOCK</code>s are now stored |
---|
1180 | internally as |
---|
1181 | strings, regardless of whether they correspond to "official" SLHA |
---|
1182 | blocks or not. Their contents can subsequently be queried by a set |
---|
1183 | of new templated member functions of the |
---|
1184 | class <code>SusyLesHouches</code>. Available query functions so far |
---|
1185 | include |
---|
1186 | <br/><code>template <class T> bool getEntry(string, T&);</code>, |
---|
1187 | <br/><code>template <class T> bool getEntry(string, int, T&);</code>, |
---|
1188 | <br/><code>template <class T> bool getEntry(string, int, int, T&); |
---|
1189 | </code>, and |
---|
1190 | <br/><code>template <class T> bool getEntry(string, int, |
---|
1191 | int, int, T&);</code>, |
---|
1192 | <br/>where the type of |
---|
1193 | the argument used in the call determines how to read the block |
---|
1194 | entries. Thus, if an LHEF, SLHA, or other card file is read in by |
---|
1195 | PYTHIA, the contents of any <code>BLOCK</code> in that file can |
---|
1196 | subsequently be queried run-time using these functions. This is |
---|
1197 | used, e.g., in the new interface between MADGRAPH 5 and PYTHIA |
---|
1198 | 8. Thanks to the MADGRAPH team, and to J. Alwall in particular, for |
---|
1199 | help and debug on this new implementation. |
---|
1200 | </li> |
---|
1201 | |
---|
1202 | </ul> |
---|
1203 | </li> |
---|
1204 | |
---|
1205 | <li>8.153: 10 August 2011 |
---|
1206 | <ul> |
---|
1207 | |
---|
1208 | <li>The setup of tunes has been modified, see the |
---|
1209 | <aloc href="Tunes">Tunes</aloc> page for details. Specifically |
---|
1210 | the <code>Tune:ee</code> and <code>Tune:pp</code> modes have |
---|
1211 | acquired a new option <code>-1</code> for a forced restore to the |
---|
1212 | default values of all settings used in the respective kind of |
---|
1213 | tunes.</li> |
---|
1214 | |
---|
1215 | <li>The code for handling multiparton interactions in the scenario with |
---|
1216 | an <ei>x</ei>-dependent width of the Gaussian matter profile |
---|
1217 | <ref>Cor11</ref>, has been improved and updated. Tune 4Cx, which |
---|
1218 | is based on this option, has been added as a further tune option.</li> |
---|
1219 | |
---|
1220 | <li>A possibility to bias the phase-space selection has been added, |
---|
1221 | whereby some phase space regions can be oversampled, which is |
---|
1222 | compensated by assigning a weight to each event. |
---|
1223 | A new set of methods have been added to the <code>UserHooks</code> |
---|
1224 | class to allow users to program how to bias the selection.</li> |
---|
1225 | |
---|
1226 | <li>New options added so that matrix-element corrections can be |
---|
1227 | switched off after the first branching in ISR or FSR.</li> |
---|
1228 | |
---|
1229 | <li>Some new <code>Info</code> methods have been added to store |
---|
1230 | information on latest ISR branching. The <code>SpaceShower</code> |
---|
1231 | class has also been corrected so that the latest <ei>z = 1/2</ei> |
---|
1232 | when not defined by history. This avoids undefined values for |
---|
1233 | azimuthal asymmetries. Thanks to Stefan Prestel for finding and |
---|
1234 | sorting out this problem.</li> |
---|
1235 | |
---|
1236 | <li>The <code>Pythia::forceHadronLevel()</code> method now takes |
---|
1237 | an argument that optionally means that existing junction information |
---|
1238 | is not overwritten. Thanks to Leif Lönnblad for pointing out |
---|
1239 | the usefulness of this.</li> |
---|
1240 | |
---|
1241 | <li>For particle decays to a varying number of hadrons the multiplicity |
---|
1242 | increase with mass has been somewhat reduced, and especially for |
---|
1243 | <code>meMode = 23</code> a separate even slower increase has been |
---|
1244 | introduced.</li> |
---|
1245 | |
---|
1246 | <li>New possibility to force the tau polarization.</li> |
---|
1247 | |
---|
1248 | <li>Bug fix for the special case in which events containing SUSY |
---|
1249 | particles are generated without proper initialization of SUSY decays. |
---|
1250 | This can happen, e.g., if events containing SUSY particles are read |
---|
1251 | in via external LHEF files, if those files do not contain readable |
---|
1252 | SLHA spectra in their headers. In this case, a failed attempt to |
---|
1253 | generate sparticle decays with ill-defined couplings previously |
---|
1254 | led to crashes. The program now reverts to the old behaviour, |
---|
1255 | based on static decay tables, in such cases, with the default |
---|
1256 | being to decay all sparticles to gravitino + particle. An error |
---|
1257 | message stating that the full SUSY treatment has been switched |
---|
1258 | off and why is also issued. Thanks to N. Desai for this fix.</li> |
---|
1259 | |
---|
1260 | <li>The R-hadron machinery has been completed.</li> |
---|
1261 | |
---|
1262 | <li>Minor change in timelike showers: gluons which fall below the |
---|
1263 | <ei>pTmin</ei> cutoff by the correction for mass effects are now |
---|
1264 | eliminated, while previously they were kept. This reduces the |
---|
1265 | number of gluons somewhat, but has no significant effects on the |
---|
1266 | hadronic final state. (Prompted by R-hadron studies, where big mass |
---|
1267 | effects else give bothersome low-energy gluons.)</li> |
---|
1268 | |
---|
1269 | <li>Corrected typos in two of the Upsilon wave function matrix |
---|
1270 | elements, <code>Bottomonium:OUpsilon3P08</code> and |
---|
1271 | <code>Bottomonium:Ochib03P01</code>. Thanks to Beate Heinemann for |
---|
1272 | pointing it out.</li> |
---|
1273 | |
---|
1274 | <li>Implemented <ei>f*</ei> decay angle in <ei>f f -> f f*</ei> processes, |
---|
1275 | and fixed some bugs for the same process. Thanks to Piyali Banerjee |
---|
1276 | for tests.</li> |
---|
1277 | |
---|
1278 | <li>Introduce possibility to separate production channels for |
---|
1279 | TeV-sized extra dimensions, and a small code correction. Thanks to |
---|
1280 | Noam Hod for code contribution.</li> |
---|
1281 | |
---|
1282 | <li>Bug fix for neutrino beams: since neutrinos are always lefthanded |
---|
1283 | there should be a factor 2 in the cross section, relative to charged |
---|
1284 | leptons, from the non-need to average over incoming spin states. This |
---|
1285 | is now fixed by introducing a new PDF class <code>NeutrinoPoint</code> |
---|
1286 | for (unresolved) neutrinos, with normalization 2 rather than 1 for |
---|
1287 | charged leptons. Thanks to Ryosuke Sato.</li> |
---|
1288 | |
---|
1289 | <li>Bug fix for some (rarely used) particle settings, which could not |
---|
1290 | be changed by users because they were read too early. Thanks to |
---|
1291 | Andrew Altheimer and Gustaaf Brooijmans.</li> |
---|
1292 | |
---|
1293 | <li>Bug fix in handling of <code>tau</code> decays, where setting of |
---|
1294 | decay vertices could write outside memory. Thanks to Steven Schramm.</li> |
---|
1295 | |
---|
1296 | <li>Minor expansion of the <code>BeamParticle</code> constructor.</li> |
---|
1297 | |
---|
1298 | <li>Minor bug fix in CTEQ 6L for uninitialized variables.</li> |
---|
1299 | |
---|
1300 | <li>Minor bug fix in fragmentation flavour combination to hadron.</li> |
---|
1301 | |
---|
1302 | <li>Some updates of the documentation, including new pages on |
---|
1303 | MadGraph 5 as a generator for semi-internal processes (thanks to |
---|
1304 | Johan Alwall) and on RIVET interfacing.</li> |
---|
1305 | |
---|
1306 | <li>Minor improvements of ROOT- and HepMC-related code and documentation.</li> |
---|
1307 | |
---|
1308 | <li>Some cleanup of code.</li> |
---|
1309 | |
---|
1310 | </ul> |
---|
1311 | </li> |
---|
1312 | |
---|
1313 | <li>8.157: 10 November 2011 |
---|
1314 | <ul> |
---|
1315 | |
---|
1316 | <ii>StefanPrestel joins as new member of the PYTHIA author team. |
---|
1317 | He is mainly working on matching/merging issues, and has contributed |
---|
1318 | the CKKW-L machinery mentioned below.</li> |
---|
1319 | |
---|
1320 | <li>Merging capabilities according to the CKKW-L scheme <ref>Lon11</ref> |
---|
1321 | have been added, see the new |
---|
1322 | <aloc href="MatrixElementMerging">Matrix Element Merging</aloc> |
---|
1323 | page. It involves new classes to reconstruct and select how a |
---|
1324 | matrix-element-generated partonic configuration could have been obtained |
---|
1325 | by the PYTHIA evolution, and to perform trial showers (using a new |
---|
1326 | copy of the normal parton-level machinery) that introduce the appropriate |
---|
1327 | Sudakov suppression factors. New examples to illustrate various |
---|
1328 | common tasks are found in <code>main81.cc</code>, <code>main82.cc</code>, |
---|
1329 | <code>main83.cc</code> and <code>main84.cc</code>.</li> |
---|
1330 | |
---|
1331 | <li>The <code>main71.cc</code> program is now generalised for reading |
---|
1332 | in arbitrary POWHEG LHE files, to implement a smooth matching between NLO |
---|
1333 | matrix elements and the PYTHIA parton showers. Cuts are made on both |
---|
1334 | ISR and FSR emissions, while previously only ISR was covered. The key |
---|
1335 | assumptions are the <ei>pT</ei> definitions used for ISR and FSR, but several |
---|
1336 | further options are available, as documented in the <code>main71.cmnd</code> |
---|
1337 | file. Work is still ongoing to pick the best default options. </li> |
---|
1338 | |
---|
1339 | <li>Several expansions of the <code>UserHooks</code> class. |
---|
1340 | For both <code>doVetoFSREmission</code> and <code>doVetoISREmission</code> |
---|
1341 | a new argument <code>iSys</code> labels the system within which the |
---|
1342 | radiation occurs. For <code>doVetoFSREmission</code> a further argument |
---|
1343 | <code>inResonance</code> distinguishes FSR in resonance |
---|
1344 | decays from that in the hard process itself. New methods |
---|
1345 | <code>canVetoMPIEmission</code> and <code>doVetoMPIEmission</code> |
---|
1346 | have been added to veto multiparton interactions in the same way as |
---|
1347 | FSR and ISR. In <code>biasSelectionBy</code> at times incorrect values |
---|
1348 | for <code>inEvent</code> has been corrected. Also some systematization |
---|
1349 | of the use of <code>const</code>.</li> |
---|
1350 | |
---|
1351 | <li>A new model for hadron scattering is introduced, still at an early |
---|
1352 | stage and therefore more intended for internal development than for the |
---|
1353 | normal user. The basic idea is that a high-energy <ei>pp</ei> collision |
---|
1354 | involves the fragmentation of multiparton strings that overlap in space |
---|
1355 | (and time). Also the produced hadrons therefore initially overlap, and |
---|
1356 | there is a strong likelihood that hadrons can scatter against each other |
---|
1357 | until the system has expanded sufficiently. This can e.g. increase the |
---|
1358 | transverse momentum of heavier hadrons at the expense of lighter ones. |
---|
1359 | </li> |
---|
1360 | |
---|
1361 | <li>A new jet finder <code>SlowJet</code> offers simple access to the |
---|
1362 | inclusive <ei>kT</ei>, anti-<ei>kT</ei>, and Cambridge/Aachen |
---|
1363 | algorithms in a cylindrical coordinate frame. The jet reconstruction |
---|
1364 | is then based on sequential recombination with progressive removal, |
---|
1365 | using the <ei>E</ei> recombination scheme. The minimalistic |
---|
1366 | <code>SlowJet</code> code is much slower than <code>FastJet</code> |
---|
1367 | <ref>Cac06</ref>, and contains less options, but reconstructs the same |
---|
1368 | jets if run under identical conditions. For details see the |
---|
1369 | <aloc href="EventAnalysis">Event Analysis</aloc> page.</li> |
---|
1370 | |
---|
1371 | <li>Starting in gcc 4.6, it is possible to switch off specific warnings |
---|
1372 | around specific blocks of code. Although version 4.6 is some way off |
---|
1373 | from being commonly found, this option has now been introduced to switch |
---|
1374 | off <code>-Wshadow</code> warnings in <code>HepMCInterface.cc</code>. |
---|
1375 | For other compilers, or earlier versions of gcc, the old behaviour |
---|
1376 | is retained.</li> |
---|
1377 | |
---|
1378 | <li>Support for reading in gzipped LHEFs has been added in the |
---|
1379 | <code>LesHouches</code> and <code>SusyLesHouches</code> classes. |
---|
1380 | This also affects <code>configure</code> and <code>Makefile</code>s. |
---|
1381 | Unless explicitly enabled, it should not affect anything. |
---|
1382 | If enabled, it relies on the Boost and zlib libraries to function, |
---|
1383 | so paths to these must be set appropriately, see the |
---|
1384 | <code>README</code> file for details. The Boost header files can |
---|
1385 | give very many shadow warnings, so <code>-Wshadow</code> is disabled |
---|
1386 | if gzip support is enabled, as described above.</li> |
---|
1387 | |
---|
1388 | <li>Introduce use of the <code>HEPMC_HAS_UNITS</code> environment |
---|
1389 | variable in the <code>HepMCInterface.cc</code> and <code>main32.cc</code> |
---|
1390 | codes to automatically check whether GeV and mm can be set as relevant |
---|
1391 | units. If yes, then it is set in <code>main32.cc</code>. If no, |
---|
1392 | a conversion from GeV to MeV is done explicitly in |
---|
1393 | <code>HepMCInterface.cc</code>. Note that, for early HepMC versions, |
---|
1394 | this means a change of behaviour. Thanks to Andy Buckley.</li> |
---|
1395 | |
---|
1396 | <li>A new method <code>Info::lhaStrategy()</code> returns the |
---|
1397 | Les Houches event weighting strategy where relevant, and 0 where not. |
---|
1398 | For the strategies <ei>+-4</ei> the event weight and sum, |
---|
1399 | <code>Info::weight()</code> and <code>Info::weightSum()</code>, |
---|
1400 | is now in units of pb at output, as it should be at input. |
---|
1401 | (While internally mb is used.)</li> |
---|
1402 | |
---|
1403 | <li>New flag <code>Check:abortIfVeto</code> allows the user to |
---|
1404 | resume control over execution in case of a veto in the event |
---|
1405 | generation process.</li> |
---|
1406 | |
---|
1407 | <li>New method <code>Event::at(i)</code> returns reference to |
---|
1408 | <code>i</code>'th particle in the event record.</li> |
---|
1409 | |
---|
1410 | <li>Introduce the Fermi constant as one of the Standard Model |
---|
1411 | parameters.</li> |
---|
1412 | |
---|
1413 | <li>Included automatic pre-initialization of SLHA blocks MASS and |
---|
1414 | SMINPUTS using PYTHIA's SM parameters and particle data table |
---|
1415 | values.</li> |
---|
1416 | |
---|
1417 | <li>SUSY: added sleptons (and sneutrinos) as resonances. |
---|
1418 | Corrected 2-body decay widths of gluinos, squarks and gauginos. |
---|
1419 | Added sleptonic decay modes to gaugino decays. |
---|
1420 | Implemented 2-body decays of sleptons (and sneutrinos) |
---|
1421 | into sleptons/leptons/gauginos. Corrected slepton couplings (they |
---|
1422 | now look exactly like squark couplings, using a 6x6 slepton mixing |
---|
1423 | matrix).</li> |
---|
1424 | |
---|
1425 | <li>New parameter <code>Diffraction:probMaxPert</code> introduce to |
---|
1426 | give more flexibility in transition from a nonperturbative to a |
---|
1427 | perturbative description of a diffractive system.</li> |
---|
1428 | |
---|
1429 | <li>Bug corrected in <code>SigmaEW.cc</code>, for the process |
---|
1430 | <code>WeakSingleBoson:ffbar2ffbar(s:gm)</code>. Previously, all outgoing |
---|
1431 | quark flavours in this process were erroneously assigned ID code 5 |
---|
1432 | (b quarks). This has now been corrected so the proper ratios are |
---|
1433 | obtained, with <ei>u : c : d : s : b = 4 : 4 : 1 : 1 : 1</ei>, |
---|
1434 | according to the squared quark charges.</li> |
---|
1435 | |
---|
1436 | <li>Changes in <code>FragmentationSystems</code> and |
---|
1437 | <code>StringFragmentation</code> to reject systems with three or more |
---|
1438 | interconnected junctions. This may happen in baryon-number-violating |
---|
1439 | scenarios in pp collisions, if both of the beam baryon junctions are |
---|
1440 | resolved and get connected via an antijunction created by a |
---|
1441 | hard-process BNV vertex. In principle, this could be addressed by an |
---|
1442 | extension of the existing junction fragmentation framework. However, |
---|
1443 | since it happens rarely, for the time being an error message is printed |
---|
1444 | and the fragmentation restarted. |
---|
1445 | </li> |
---|
1446 | |
---|
1447 | <li>Change in <code>Event::copy</code> to safeguard against attempting |
---|
1448 | to copy out-of-range entries. An attempt to copy a non-existing entry |
---|
1449 | will now return -1.</li> |
---|
1450 | |
---|
1451 | <li>Bug fix in the machinery for the user to force the setting of |
---|
1452 | tau polarization.</li> |
---|
1453 | |
---|
1454 | <li>Bug fix in the initial search for a maximum of the process |
---|
1455 | cross section (only affecting rare cases).</li> |
---|
1456 | |
---|
1457 | <li>Corrected angular decay distributions for two compositeness |
---|
1458 | processes, <code>Sigma2qq2qStarq</code> and |
---|
1459 | <code>Sigma2qqbar2lStarlbar</code>.</li> |
---|
1460 | |
---|
1461 | <li>Extra check in <code>HiddenValleyFragmentation</code> to make sure |
---|
1462 | that pointers which have not been assigned with <code>new</code> are not |
---|
1463 | deleted.</li> |
---|
1464 | |
---|
1465 | <li>Some further minor changes.</li> |
---|
1466 | |
---|
1467 | </ul> |
---|
1468 | </li> |
---|
1469 | |
---|
1470 | <li>8.160: 23 January 2012 |
---|
1471 | <ul> |
---|
1472 | |
---|
1473 | <li>The older term "multiple interactions" has been replaced by the |
---|
1474 | new standard "multiparton interactions" one, and correspondingly the |
---|
1475 | abbreviation MI by MPI. This affects everything: settings, class and |
---|
1476 | method names, documentation, etc. It therefore becomes necessary to |
---|
1477 | rewrite user code. However, so as to keep the immediate effort at a |
---|
1478 | reasonable level, the old settings names are kept as aliases. Thus |
---|
1479 | <code>PartonLevel:MI</code> and <code>PartonLevel:MPI</code> are |
---|
1480 | equivalent, and similarly <code>MultipleInteractions:pT0Ref</code> |
---|
1481 | and <code>MultipartonInteractions:pT0Ref</code>. Should you be using |
---|
1482 | methods such as <code>double Info::pTMI(int i)</code> you need to |
---|
1483 | edit the code, however. All the <code>example/main*</code> files |
---|
1484 | have been uopdated accordingly.</li> |
---|
1485 | |
---|
1486 | <li>A new option <code>Beams:frameType = 5</code> has been added |
---|
1487 | for the case where an external generator should provide LHA process |
---|
1488 | information. The new <code>Pythia::setLHAupPtr(...)</code> method |
---|
1489 | should then be used to link in this generator. The new switch |
---|
1490 | <code>Beams:newLHEFsameInit</code> can be used to tell that a new |
---|
1491 | LHEF should be used, but without the need for a new initialization. |
---|
1492 | With these two changes, all the different ways of initializing |
---|
1493 | can be covered by the <code>Pythia::init()</code> call with no |
---|
1494 | arguments. The various <code>init(...)</code>options with arguments |
---|
1495 | are deprecated and will be removed for PYTHIA 8.2.</li> |
---|
1496 | |
---|
1497 | <li> The <code>Pythia::stat()</code> method, with no arguments, |
---|
1498 | replaces <code>Pythia::statistics(...)</code>, although the latter |
---|
1499 | remains as a deprecated alternative.</li> |
---|
1500 | |
---|
1501 | <li>New settings <code>Init:...</code>, <code>Next:...</code>, |
---|
1502 | and <code>Stat:...</code> can be used to steer some details of |
---|
1503 | the operation of the <code>Pythia::init()</code>, |
---|
1504 | <code>Pythia::next()</code> and <code>Pythia::stat()</code>, |
---|
1505 | respectively. In particular it affects the amount of printout |
---|
1506 | at the various stages of operation. See |
---|
1507 | <aloc href="MainProgramSettings">here</aloc> for further details. |
---|
1508 | This change involves several code changes, but in documentation |
---|
1509 | rather than physics. Most of the <code>Main:...</code> settings |
---|
1510 | are deprecated as a consequence.</li> |
---|
1511 | |
---|
1512 | <li>The sample main programs in the <code>examples</code> subdirectory |
---|
1513 | have been updated. This includes a change to the new favoured |
---|
1514 | methods and settings outlined above, plus some update of the |
---|
1515 | physics contents. Some of the examples have been combined, |
---|
1516 | some others have been added (e.g. for R-hadroms), and as a consequence |
---|
1517 | some renumbering has been made. See the modified list of |
---|
1518 | <aloc href="SampleMainPrograms">sample main programs</aloc> for |
---|
1519 | the new status. In particular note that (the new) <code>main61.cc</code> |
---|
1520 | allows streamlined input and output in HepMC, like <code>main42.cc</code> |
---|
1521 | (previously <code>main32.cc</code>), but additionally links to LHAPDF. </li> |
---|
1522 | |
---|
1523 | <li>The <code>examples/configure</code> script has new optional argument |
---|
1524 | <code>--with-pythia8</code>. It can be used to set the new |
---|
1525 | <code>PYTHIA8LOCATION</code> environment variable, which then is used |
---|
1526 | in <code>examples/Makefile</code> to give the path to the PYTHIA |
---|
1527 | library. Thereby it becomes possible to relocate (parts of) the |
---|
1528 | <code>examples</code> directory and still obtain the correct path. |
---|
1529 | Thanks to Mikhail Kirsanov.</li> |
---|
1530 | |
---|
1531 | <li>Polarization information has been included as a new |
---|
1532 | <code>Particle</code> property, that can be set by |
---|
1533 | <code>void pol(double polIn)</code> and obtained by |
---|
1534 | <code>double pol()</code>. Default value is <code>9.</code>, |
---|
1535 | in agreement with the Les Houches standard. Event listings have |
---|
1536 | been expanded to optionally display this information. Currently |
---|
1537 | polarization is not used internally.</li> |
---|
1538 | |
---|
1539 | <li>The matrix element merging machinery has been modified as follows. |
---|
1540 | <br/>- Improved handling of the hard process, so that MadGraph5-produced |
---|
1541 | LHE files do not produce problems (sometimes, the choices of MG4 on what |
---|
1542 | to put into a LHEF have changed in MG5). |
---|
1543 | <br/>- Improved handling of colour for easier handling of states with |
---|
1544 | many quarks (the code has been tested for states with up to 5 |
---|
1545 | <ei>q qbar</ei> pairs and some gluons). |
---|
1546 | <br/>- Improved checking which clusterings are allowed. Now, clusterings |
---|
1547 | should immediately be rejected if they lead to unphysical states, |
---|
1548 | without the need to explicitly construct these states. This was needed |
---|
1549 | to get <ei>t tbar</ei> production, VBF and some simple SUSY processes |
---|
1550 | running with reasonable generality. |
---|
1551 | <br/>- Improved handling of incomplete histories. Now there is an |
---|
1552 | additional switch allowing code to try to swap some colours when fewer |
---|
1553 | clusterings than requested have been found. |
---|
1554 | </li> |
---|
1555 | |
---|
1556 | <li>Updates in the handling of graviton resonances in scenarios with |
---|
1557 | extra dimensions. |
---|
1558 | <br/>- Now all G decays have correct angular distribution, which was not |
---|
1559 | the case before for W/Z decays. |
---|
1560 | <br/>- Added the possibility for G to only couple to longitudinal |
---|
1561 | W/Z bosons, which affects both the width and angular distributions. |
---|
1562 | <br/>- Added decays to Higgs pairs, <ei>G -> hh</ei>. |
---|
1563 | </li> |
---|
1564 | |
---|
1565 | <li>Bug fix in the <code>findJunctions()</code> function in |
---|
1566 | <code>ProcessLevel.cc</code>. Changes introduced in version |
---|
1567 | 8.145 (to allow for junctions in baryon-number-violating |
---|
1568 | processes) did not correctly handle the remapping of color |
---|
1569 | tags that can be applied when adding beam remnants to events with |
---|
1570 | multiparton interactions. A simpler and more stable algorithm is |
---|
1571 | now applied for the simplest cases, with the more complex one only |
---|
1572 | invoked for cases such as BNV, which are normally considered before |
---|
1573 | remnants are added, hence avoiding this particular problem. Also some |
---|
1574 | other changes in the handling of junction, including a safeguard to |
---|
1575 | reject systems with three or more interconnected junctions.</li> |
---|
1576 | |
---|
1577 | <li>Bug fix and updates to the SLHA interface. Possibility of infinite |
---|
1578 | loop during <code>ProcessLevel::initSLHA</code> corrected. Modifications |
---|
1579 | to <code>SusyLesHouches</code> to allow interpretation of SLHA1 spectra |
---|
1580 | with R-parity violation. Rather than reject spectra that do not conform |
---|
1581 | fully to the SLHA2 standard for RPV, the interface will now first look |
---|
1582 | for SLHA1 mixing matrices and attempt to translate those into SLHA2 ones |
---|
1583 | if possible. In this case, warnings that the expected SLHA2 blocks were |
---|
1584 | not found will be printed. It is up to the user to check that the |
---|
1585 | derived SLHA2 information is correct. Corresponding additions to |
---|
1586 | <code>SusyCouplings.cc</code> to extract mixing-matrix information |
---|
1587 | from the relevant SLHA2 RPV blocks when RPV is switched on.</li> |
---|
1588 | |
---|
1589 | <li>Updated SLHA example <code>main24.cmnd</code> to use new example |
---|
1590 | spectrum, <code>cmssm.spc</code>, corresponding to CMSSM point |
---|
1591 | 10.1.1, obtained with SOFTSUSY 3.3.0. Thanks to B. Allanach for |
---|
1592 | providing the new spectrum file.</li> |
---|
1593 | |
---|
1594 | <li>A new <code>include/FastJet3.h</code> header file simplifies |
---|
1595 | interfacing of FastJet to Pythia. For details see documentation in |
---|
1596 | the file itself. Thanks to Gavin Salam for this contribution.</li> |
---|
1597 | |
---|
1598 | <li>The handling of diffraction has been made more flexible. |
---|
1599 | Specifically the "total" Pomeron-proton cross section can now be made |
---|
1600 | to depend on the mass of the diffractive system. This does not affect |
---|
1601 | the diffractive cross section in pp collisions, which is set separately, |
---|
1602 | but is used in the MPI machinery to affect the average number of |
---|
1603 | interactions per Pomeron-proton collision. Furthermore, the allowed |
---|
1604 | range for some parameters has been expanded. Thanks to Robert |
---|
1605 | Ciesielski.</li> |
---|
1606 | |
---|
1607 | <li>New method <code>Pythia::forceTimeShower(...)</code> can be used to |
---|
1608 | generate a single final-state cascade from a set of partons, without |
---|
1609 | any knowledge of prior history. This is mainly intended for toy studies. |
---|
1610 | The meaning of the <code>ProcessLevel:all</code> switch has been modified |
---|
1611 | so that this parton-level function is available, but not any others |
---|
1612 | at this level. |
---|
1613 | </li> |
---|
1614 | |
---|
1615 | <li>ATLAS tune A2 now included. Thanks to Deepak Kar for |
---|
1616 | providing it.</li> |
---|
1617 | |
---|
1618 | <li>Change in the handling of recoils of timelike showers in resonance |
---|
1619 | decays, in cases of coloured resonances such as <ei>t -> b W</ei>. In |
---|
1620 | the first step the <ei>W</ei> always acts as recoiler to the <ei>b</ei>, |
---|
1621 | but in subsequent step previously the <ei>W</ei> remained as recoiler to |
---|
1622 | one dipole, while now all QCD-radiating partons recoil against another |
---|
1623 | coloured parton. The old behaviour could give a (small) unphysical spike |
---|
1624 | of radition collinear with the colourless recoiler in the subsequent |
---|
1625 | emissions (while the pattern of the first was and remains correct). |
---|
1626 | The old behaviour can be recovered for checks, see |
---|
1627 | <code>TimeShower:recoilToColoured</code>. |
---|
1628 | Thanks to Yevgeny Kats for pointing out this issue (previously noted |
---|
1629 | for Pythia 6 by several persons). |
---|
1630 | </li> |
---|
1631 | |
---|
1632 | <li>Bug fixes for <code>rootexamples/Makefile</code> and restoration |
---|
1633 | of some deleted information in <code>rootexamples/README</code>. |
---|
1634 | Thanks to Axel Naumann and Bernhard Meirose.</li> |
---|
1635 | |
---|
1636 | <li>Bug fix, so that displaced vertices are possible in resonance |
---|
1637 | decay chains. Thanks to Daniel Blackburn and Andy Buckley for |
---|
1638 | pointing this out.</li> |
---|
1639 | |
---|
1640 | <li>Bug fix for <code>Info</code> counter 2.</li> |
---|
1641 | |
---|
1642 | <li>Bug fix so that sextet quarks now are read in correctly from |
---|
1643 | Les Houches Event files; previously the (anti)colours were set |
---|
1644 | to 0.</li> |
---|
1645 | |
---|
1646 | <li>Year updated to 2012 in copyright statements etc.</li> |
---|
1647 | |
---|
1648 | <li>Reformatting to reduce the number of code lines with more |
---|
1649 | than 79 characters.</li> |
---|
1650 | |
---|
1651 | <li><code>Pythia::initSLHA()</code> moved from <code>public</code> |
---|
1652 | to <code>private</code>. |
---|
1653 | </li> |
---|
1654 | |
---|
1655 | <li>Remove warning message when tau polarization is set by hand.</li> |
---|
1656 | |
---|
1657 | <li>Several minor changes to reduce the number of warnings issued |
---|
1658 | by the clang compiler. The origin of some warnings remains unclear |
---|
1659 | so those remain to track down (could also be compiler bugs; note that |
---|
1660 | we discuss warnings, not errors). Thanks to Randy MacLeod for bringing |
---|
1661 | this up.</li> |
---|
1662 | |
---|
1663 | <li>The worksheet has been updated to be in step with Pythia 8.160.</li> |
---|
1664 | |
---|
1665 | <li>Several other minor corrections in the code and documentation.</li> |
---|
1666 | |
---|
1667 | </ul> |
---|
1668 | </li> |
---|
1669 | |
---|
1670 | <li>8.162: 12 March 2012 |
---|
1671 | <ul> |
---|
1672 | |
---|
1673 | <li>A new option allows for several partons to share the recoil in |
---|
1674 | final-state radiation, see<aloc href="TimelikeShowers">Timelike |
---|
1675 | Showers</aloc>. It is mainly intended to be used in the context of |
---|
1676 | matching to matrix elements, and so only to be used in the first |
---|
1677 | few branchings.</li> |
---|
1678 | |
---|
1679 | <li>Several new processes for LED dijet production, see |
---|
1680 | <aloc href="ExtraDimensionalProcesses">Extra Dimensions</aloc>.</li> |
---|
1681 | |
---|
1682 | <li>Small update of the <code>Sigma2ffbar2LEDllbar</code> and |
---|
1683 | <code>Sigma2ffbar2LEDgammagamma</code> LED processes.</li> |
---|
1684 | |
---|
1685 | <li>New <code>Sigma2QCffbar2llbar</code> |
---|
1686 | <aloc href="CompositenessProcesses">contact interaction</aloc> |
---|
1687 | process.</li> |
---|
1688 | |
---|
1689 | <li>Inclusion of a new method in the |
---|
1690 | <aloc href="MatrixElementMerging">matrix-element merging</aloc> |
---|
1691 | framework to influence the construction of histories, e.g. to already |
---|
1692 | in the construction of histories disallow paths that fail the |
---|
1693 | <ei>2 -> 2</ei> cuts.</li> |
---|
1694 | |
---|
1695 | <li>Further minor updates of the matrix-element merging code, |
---|
1696 | mainly for improved clarity.</li> |
---|
1697 | |
---|
1698 | <li>Minor bug fix in the handling of beam and event information fed |
---|
1699 | in from an <code>LHAup</code> instance.</li> |
---|
1700 | |
---|
1701 | <li>Minor bug fix for potential crashes from uninitialized variables |
---|
1702 | for the merging machinery when merging is not used.</li> |
---|
1703 | |
---|
1704 | <li>Updated History class for matrix element merging, |
---|
1705 | also avoiding some compiler warnings.</li> |
---|
1706 | |
---|
1707 | <li>Bug fixes in the handling of correlated mass choices in resonance |
---|
1708 | decays, such as <ei>H -> Z^*0 Z^*0</ei>.</li> |
---|
1709 | |
---|
1710 | <li>Bug fix when the process-level execution is switched off, |
---|
1711 | where <code>Info::isResolved()</code> could be called before its |
---|
1712 | value was initialized. Thanks to Christian Pulvermacher |
---|
1713 | for finding this.</li> |
---|
1714 | |
---|
1715 | <li>Corrected matrix-element expression for mass selection in |
---|
1716 | <ei>A^0 -> Z^*0 Z^*0</ei> and <ei>A^0 -> W^*+ W^*-</ei>.</li> |
---|
1717 | |
---|
1718 | <li>SM Higgs mass updated to 125 GeV and default width and branching |
---|
1719 | ratios modified accordingly. Minor technical improvements of width |
---|
1720 | calculation.</li> |
---|
1721 | |
---|
1722 | <li>The usage of nested classes has been removed from |
---|
1723 | <code>SusyLesHouches</code>, since it could give compilation errors |
---|
1724 | on some platforms. The new class names begin with <code>LH</code> |
---|
1725 | and all classes have been put inside the <code>Pythia8</code> |
---|
1726 | namespace.</li> |
---|
1727 | |
---|
1728 | <li>Minor Makefile updates. Thanks to Mikhail Kirsanov.</li> |
---|
1729 | |
---|
1730 | <li>Minor changes to avoid some clang compiler warnings on the |
---|
1731 | Mac OS X platform.</li> |
---|
1732 | |
---|
1733 | </ul> |
---|
1734 | </li> |
---|
1735 | |
---|
1736 | <li>8.163: 27 March 2012 |
---|
1737 | <ul> |
---|
1738 | |
---|
1739 | <li>New methods in the |
---|
1740 | <aloc href="EventInformation"><code>Info</code></aloc> class, |
---|
1741 | <code>id1pdf()</code>, <code>id2pdf()</code>, <code>x1pdf()</code> |
---|
1742 | and <code>x2pdf()</code>, to denote the partons for which parton |
---|
1743 | distribution values have been defined. Previously this was assumed |
---|
1744 | to agree with the incoming partons to the hard process, the same |
---|
1745 | methods without the <code>pdf</code> qualifier. However, now the |
---|
1746 | POWHEG approach offers a counterexample. Also the reading and |
---|
1747 | handling of Les Houches (and other) events, and the interface |
---|
1748 | to HepMC, has been modified accordingly. |
---|
1749 | </li> |
---|
1750 | |
---|
1751 | <li>The decay of Higgs and top resonances read in from Les Houches |
---|
1752 | Event files is now performed with angular correlations as for |
---|
1753 | internal processes. LHE files should normally contain all process-specific |
---|
1754 | resonance decay chains and, if not, decays are made isotropic. |
---|
1755 | The <ei>H -> WW/ZZ -> f fbar f' fbar'</ei> and |
---|
1756 | <ei>t -> b W -> b f fbar</ei> correlations are process-independent, |
---|
1757 | however, and thus can be handled internally. If part of the decay |
---|
1758 | chain has already been set, e.g. <ei>H -> WW/Z></ei> or <ei>t -> b W</ei>, |
---|
1759 | then the subsequent decays are still isotropic.</li> |
---|
1760 | |
---|
1761 | <li>Updated instructions how to link to HepMC, |
---|
1762 | in <code>README.HepMC</code>.</li> |
---|
1763 | |
---|
1764 | <li>Bug fix in the turn-on of resolved diffraction for low |
---|
1765 | CM energies. Thanks to Erwin Visser.</li> |
---|
1766 | |
---|
1767 | <li>Bug fix in the handling of string junctions at very high energies, |
---|
1768 | caused by numerical errors. Thanks to Erwin Visser.</li> |
---|
1769 | |
---|
1770 | <li>Some other small changes, mainly aesthetics.</li> |
---|
1771 | |
---|
1772 | </ul> |
---|
1773 | </li> |
---|
1774 | |
---|
1775 | <li>8.165: 8 May 2012 |
---|
1776 | <ul> |
---|
1777 | |
---|
1778 | <li>The MBR (Minimum Bias Rockefeller) model for single, double and |
---|
1779 | central diffraction <ref>Cie12</ref> is included as new option |
---|
1780 | <aloc href="Diffraction"><code>Diffraction:PomFlux = 5</code></aloc>. |
---|
1781 | It is specifically intended for <ei>p p</ei> and <ei>pbar p</ei> |
---|
1782 | interactions, and is currently the only option that also supports |
---|
1783 | central diffraction. Thus the basic machinery for Central Diffraction |
---|
1784 | (a.k.a. Double Pomeron Exchange) has now been implemented. |
---|
1785 | See <code>examples/main04.cc</code> for an example. |
---|
1786 | Thanks to Robert Ciesielski for contributing the new code. |
---|
1787 | </li> |
---|
1788 | |
---|
1789 | <li>For a <ei>tau</ei> lepton in an external process, by default the |
---|
1790 | SPINUP number in the Les Houches Accord now is interpreted as giving |
---|
1791 | the <ei>tau</ei> helicity, and is used for its decay.</li> |
---|
1792 | |
---|
1793 | <li>A <ei>tau</ei> coming from a <ei>W</ei> now defaults to being purely |
---|
1794 | lefthanded when neither of the existing matrix elements apply.</li> |
---|
1795 | |
---|
1796 | <li>Decay mode <ei>t -> H+ b</ei> included as an option.</li> |
---|
1797 | |
---|
1798 | <li>Four ATLAS tunes have been implemented as options for |
---|
1799 | <code>Tune:pp</code>: A2-minbias-mstw2008lo, AU2-cteq6l1, AU2-mstw2008lo, |
---|
1800 | and AU2-ct10. The new flag <code>Tune:preferLHAPDF</code> can be used |
---|
1801 | to switch between the LHAPDF and the internal implementation of a |
---|
1802 | PDF set, in cases where both are available.</li> |
---|
1803 | |
---|
1804 | <li>Reorder libraries in <code>examples/Makefile</code>, specifically |
---|
1805 | move <code>LIBGZIP</code> so that it is properly linked when used. |
---|
1806 | Thanks to Erik Schnetter.</li> |
---|
1807 | |
---|
1808 | <li>Minor modification so that LHAPDF can be used for PDFs in the hard |
---|
1809 | process, with one of the built-in PDFs for the rest, even if LHAPDF is |
---|
1810 | compiled so as to handle only one concurrent PDF set.</Li> |
---|
1811 | |
---|
1812 | <li>Bug fix, that <code>ParticleDecays:mixB = off</code> did not |
---|
1813 | switch off <ei>B0 - B0bar</ei> and <ei>Bs0 - Bs0bar</ei> mixing. |
---|
1814 | Thanks to James Catmore.</li> |
---|
1815 | |
---|
1816 | <li>Bug fix for the handling of gluon polarization of initial-state |
---|
1817 | radiation, where an anisotropic azimuthal distribution was inadvertently |
---|
1818 | generated in some <ei>2 -> 1</ei> processes. The update also includes |
---|
1819 | always setting the second daughter zero for the two partons coming in to |
---|
1820 | a hard <ei>2 -> 1</ei> process. Thanks to Antonio Policicchio.</li> |
---|
1821 | |
---|
1822 | <li>Bug fix, that the setting of the number of user hooks MPI steps did |
---|
1823 | not use <code>UserHooks::canVetoMPIStep()</code> properly.</li> |
---|
1824 | |
---|
1825 | <li>Some other small changes, mainly documentation and aesthetics.</li> |
---|
1826 | |
---|
1827 | </ul> |
---|
1828 | </li> |
---|
1829 | |
---|
1830 | <li>8.170: 21 September 2012 |
---|
1831 | <ul> |
---|
1832 | |
---|
1833 | <li>Streamline default behaviour and options for choice of GeV or MeV |
---|
1834 | for output to the HepMC event format, see |
---|
1835 | <aloc href="HepMCInterface">HepMC Interface</aloc>. |
---|
1836 | Also set the mass of HepMC particles explicitly, rather than having |
---|
1837 | it calculated implicitly. Thanks to James Monk and Andy Buckley.</li> |
---|
1838 | |
---|
1839 | <li>The <ei>tau</ei> decay machinery has been further augmented with |
---|
1840 | matrix elements and form factors for a variety of decay modes, such |
---|
1841 | that all modes with a branching ratio above 0.1% are fully modelled. |
---|
1842 | Several new classes and methods have been added to this end, |
---|
1843 | Also, a <ei>tau</ei> pair coming from a <ei>Z^0</ei> decay is now |
---|
1844 | handled by assuming the <ei>Z^0</ei> to be unpolarized when neither |
---|
1845 | of the existing matrix elements apply. Taus coming from B baryons are |
---|
1846 | handed as for B mesons.</li> |
---|
1847 | |
---|
1848 | <li>Flavour violating decays have been added to the squark, gluino, |
---|
1849 | neutralino and chargino decay tables.</li> |
---|
1850 | |
---|
1851 | <li>Extend the <code>UserHooks::subEvent(...)</code> method so that it |
---|
1852 | also works passably at the process level. Also new option for |
---|
1853 | <code>UserHooks::omitResonanceDecays(...)</code>.</li> |
---|
1854 | |
---|
1855 | <li>New methods <code>UserHooks::canVetoPartonLevelEarly()</code> |
---|
1856 | and <code>UserHooks::doVetoPartonLevelEarly( const Event&)</code> |
---|
1857 | are intended to be used the same way as the existing ones without |
---|
1858 | <code>Early</code> in their names, but allow veto right after |
---|
1859 | the ISR + FSR + MPI evolution, before beam remnants are added and |
---|
1860 | resonance decays are considered.</li> |
---|
1861 | |
---|
1862 | <li>Central diffraction now available for all |
---|
1863 | <code><aloc href="Diffraction">PomFlux</aloc></code> |
---|
1864 | options, not only the MBR model. This has been constructed by analogy |
---|
1865 | with the respective assumptions made for single diffraction, but |
---|
1866 | includes some arbitrariness. Therefore the cross section is left |
---|
1867 | easily rescaleable and, for backwards compatibility with tunes |
---|
1868 | that does not contain it, easily possible to switch off, see |
---|
1869 | the <aloc href="TotalCrossSections">relevant section</aloc>. |
---|
1870 | </li> |
---|
1871 | |
---|
1872 | <li>Reading of ALPGEN parameter and event files has been added, |
---|
1873 | see <aloc href="AlpgenAndMLM">ALPGEN and MLM Merging</aloc>. |
---|
1874 | </li> |
---|
1875 | |
---|
1876 | <li>MLM matching has been added, as a first step for ALPGEN events, |
---|
1877 | see <aloc href="AlpgenAndMLM">ALPGEN and MLM Merging</aloc>. |
---|
1878 | </li> |
---|
1879 | |
---|
1880 | <li>The CKKW-L merging machinery has been upgraded in a number of respects. |
---|
1881 | <br/>- More thorough treatment of <code>pp>bb~e+e-veve~</code> with |
---|
1882 | additional <ei>b</ei>-jets. |
---|
1883 | <br/>- Corrected hard <ei>mu_r</ei> and <ei>mu_f</ei> choices for |
---|
1884 | dijet and promt photon. |
---|
1885 | <br/>- More ways to define a hard process, e.g. with the LEPTONS and |
---|
1886 | NEUTRINO tags. The merging will understand LHE files for mixed processes |
---|
1887 | (e.g. <ei>W+</ei> and <ei>W-</ei> production together). |
---|
1888 | <br/>- More merging scale definitions. |
---|
1889 | <br/>- More freedom to generate all possible histories. |
---|
1890 | <br/>- Internal check (and cut) on Les Houches events in |
---|
1891 | <code>Pythia::mergeProcess</code> if merging scale value of the events |
---|
1892 | is below the value given to Pythia by setting <code>Merging::TMS</code>. |
---|
1893 | </li> |
---|
1894 | |
---|
1895 | <li>It now works to have R-parity violating decays of R-hadrons, |
---|
1896 | i.e. baryon number violation in a vertex displaced from the primary |
---|
1897 | one.</li> |
---|
1898 | |
---|
1899 | <li>The documentation of diffractive processes by the |
---|
1900 | <code><aloc href="EventInformation">Info</aloc></code> |
---|
1901 | methods has been expanded and corrected. This also include the |
---|
1902 | <code>list()</code> method.</li> |
---|
1903 | |
---|
1904 | <li>Particle masses and widths have been updated to agree with the |
---|
1905 | 2012 RPP values <ref>Ber12</ref>. Thanks to Piotr Zyla for data file |
---|
1906 | and James Catmore for program to update the PYTHIA tables from this |
---|
1907 | input.</li> |
---|
1908 | |
---|
1909 | <li>New methods <code>jetAssignment</code> and <code>removeJet</code> |
---|
1910 | added to the <code>SlowJet</code> class.</li> |
---|
1911 | |
---|
1912 | <li>Introduce angular correlation in decay chain |
---|
1913 | <ei>H -> gamma Z0 -> gamma f fbar</ei>. Thanks to Tim Barklow and |
---|
1914 | Michael Peskin.</li> |
---|
1915 | |
---|
1916 | <li>Introduce simple way to bias the selection of <ei>2 -> 2</ei> |
---|
1917 | processes towards larger <ei>pT</ei> values, with a compensatingly |
---|
1918 | decreasing event weight, see |
---|
1919 | <aloc href="PhaseSpaceCuts">Phase Space Cuts</aloc>. Only offers a |
---|
1920 | subset of the possibilities allowed by <code>UserHooks</code>, |
---|
1921 | but simpler to use. The <code>main08.cc</code> program has been |
---|
1922 | expanded to illustrate this possibility, and also expanded to |
---|
1923 | include low-<ei>pT</ei> subsamples.</li> |
---|
1924 | |
---|
1925 | <li>The two remaining non-NLO tunes from <ref>ATL12</ref> are now |
---|
1926 | included.</li> |
---|
1927 | |
---|
1928 | <li>The <code><aloc href="EventInformation">Info</aloc></code> methods |
---|
1929 | <code>nTried, nSelected, nAccepted, sigmaGen</code> and |
---|
1930 | <code>SigmaErr</code> now takes the code of an individual process |
---|
1931 | as an optional argument.</li> |
---|
1932 | |
---|
1933 | <li>It is now possible to generate resonance decays, followed by |
---|
1934 | showers and hadronization, without having them associated with any |
---|
1935 | specific process. This is part of an expanded |
---|
1936 | <aloc href="HadronLevelStandalone">Hadron-Level Standalone</aloc> |
---|
1937 | machinery, as before triggered by <code>ProcessLevel = off</code>, |
---|
1938 | but additionally requiring <code>Standalone:allowResDec = on</code>. |
---|
1939 | Input can either be directly into the <code>event</code> |
---|
1940 | event record or via a (simplified) Les Houches Event File.</li> |
---|
1941 | |
---|
1942 | <li>New <code>configure</code> script options <code>--installdir</code>, |
---|
1943 | <code>--prefix</code> and <code>--datadir</code> can be used to set the |
---|
1944 | location(s) to which the library, header and data directories |
---|
1945 | will be copied by a <code>make install</code> subsequent to the |
---|
1946 | <code>make</code>. Thanks to Mikhail Kirsanov.</li> |
---|
1947 | |
---|
1948 | <li>Fix charge in antiparticle name when particle read in from SLHA |
---|
1949 | file. Thanks to Johan Alwall.</li> |
---|
1950 | |
---|
1951 | <li>Pointers now only compared with == and != (not e.g. > 0), to avoid |
---|
1952 | warnings in gcc 4.7.</li> |
---|
1953 | |
---|
1954 | <li>New check that version number of the code matches that of the |
---|
1955 | XML files. If not, no events can be generated. Thanks to James Monk |
---|
1956 | for suggestion.</li> |
---|
1957 | |
---|
1958 | <li>New check that mother and daughter indices have been set to give |
---|
1959 | a consistent event history. Can be switched on/off with the new |
---|
1960 | <code>Check:history</code> flag.</li> |
---|
1961 | |
---|
1962 | <li>A new method <code>LHAup::newEventFile</code> has been added to |
---|
1963 | switch to reading in events from another LHE file without having to |
---|
1964 | reinitialize the whole class. Lower-level routines like |
---|
1965 | <code>openFile</code> and <code>closeFile</code> have been added to |
---|
1966 | handle correct order of operations also when an intermediate gzip |
---|
1967 | decompression step is involved.</li> |
---|
1968 | |
---|
1969 | <li><code>LHAup::eventLHEF()</code> can now be called with an optional |
---|
1970 | argument <code>false</code>, to make event files somewhat smaller by |
---|
1971 | reducing the amount of blanks.</li> |
---|
1972 | |
---|
1973 | <li>A new mode <code>Beams:nSkipLHEFatInit</code> introduced to |
---|
1974 | skip ahead the first few events in a Les Houches Event File (cf. the |
---|
1975 | <code>LHAup::skipEvent(nSkip)</code> method).</li> |
---|
1976 | |
---|
1977 | <li>Introduce a new pair of user hooks that can be used to reject |
---|
1978 | the sequence of hard-process resonance decays, without rejecting |
---|
1979 | the production of the primary resonances.</li> |
---|
1980 | |
---|
1981 | <li>The possibility of separate multiplicative prefactors to the |
---|
1982 | renormalization and factorization default <ei>pT^2</ei> scale has been |
---|
1983 | introduced for both timelike and spacelike showers.</li> |
---|
1984 | |
---|
1985 | <li>Bug fixes in history information for R-hadron production, which also |
---|
1986 | fixes HepMC conversion in this case.</li> |
---|
1987 | |
---|
1988 | <li>Bug corrected in <code>SigmaSusy.cc</code>, for chargino+neutralino |
---|
1989 | production. Indexing error for incoming quark states in the process |
---|
1990 | <code>Sigma2qqbar2charchi0</code>, resulted in incorrect CKM factors.</li> |
---|
1991 | |
---|
1992 | <li>Corrected a bug in <code>SusyLesHouches.cc</code>, for NMSSM spectra. |
---|
1993 | The unitarity check on the neutralino mixing matrix was faulty, leading |
---|
1994 | to erroneous messages about unitarity violations and SUSY being switched |
---|
1995 | off.</li> |
---|
1996 | |
---|
1997 | <li>Bug fixes in the handling of resolved and unresolved diffractive events. |
---|
1998 | Thanks to Robert Ciesielski for debug.</li> |
---|
1999 | |
---|
2000 | <li>Do not set up FSR dipoles for <ei>2 -> 1</ei> processes.</li> |
---|
2001 | |
---|
2002 | <li>Check that some channel open for resonance decays. Also further |
---|
2003 | check whether resonance decay treatment should be invoked.</li> |
---|
2004 | |
---|
2005 | <li>Bug fix in reading of particle names from SLHA input.</li> |
---|
2006 | |
---|
2007 | <li>Change mass, width and decay mode(s) of D*_s(10431). Thanks to |
---|
2008 | Michal Petran.</li> |
---|
2009 | |
---|
2010 | <li>Bug fix in leptoquark production (lepton sign in |
---|
2011 | <ei>q g -> LQ l</ei>).</li> |
---|
2012 | |
---|
2013 | <li>New argument added to <code>SpaceShower::reassignBeamPtrs</code> |
---|
2014 | for diffractive event processing, as already available for |
---|
2015 | <code>TimeShower</code>.</li> |
---|
2016 | |
---|
2017 | <li>Do not write warnings in <code>SpaceShower</code> for weights |
---|
2018 | above unity if the evolution scale is below 1 GeV^2.</li> |
---|
2019 | |
---|
2020 | <li>Add default values for member variables in some constructors, |
---|
2021 | and some related changes for <code>AlphaStrong</code> code.</li> |
---|
2022 | |
---|
2023 | <li>Warn if negative-energy parton in hadronization.</li> |
---|
2024 | |
---|
2025 | <li>The MPI <ei>pT</ei> values assumed in the beam remnant setting |
---|
2026 | of primordial <ei>kT</ei> and colour reconnection probability were |
---|
2027 | incorrect for diffractive events.</li> |
---|
2028 | |
---|
2029 | <li>The arrays with MPI information were not reset when parton or |
---|
2030 | hadron level fails and a new try is made. Only affected few events.</li> |
---|
2031 | |
---|
2032 | <li>MPI statistics can not yet be accumulated for diffractive events, |
---|
2033 | and therefore the relevant routine is no longer called.</li> |
---|
2034 | |
---|
2035 | <li>Bug fix in the double parton scattering suppression from |
---|
2036 | energy-momentum conservation.</li> |
---|
2037 | |
---|
2038 | <li>Outgoing proton masses were not set in the event record for |
---|
2039 | elastic scattering (but kinematics handling was correct).</li> |
---|
2040 | |
---|
2041 | <li>Bug fixes in the identification and documentation of junctions, |
---|
2042 | previously leading to some unnecessarily rejected events. Also |
---|
2043 | other improvements leading to fewer errors.</li> |
---|
2044 | |
---|
2045 | <li>Slightly increased values for FragmentationSystems:mJoin and |
---|
2046 | StringFragmentation::FACSTOPMASS to reduce failure rate, without |
---|
2047 | noticeably affecting event properties.</li> |
---|
2048 | |
---|
2049 | <li>The Les Houches cross section error is now taken into account |
---|
2050 | in the final Pythia error for strategies +-3. New methods |
---|
2051 | <code>LHAup::xSecSum()</code> and <code>LHAup::xErrSum()</code> |
---|
2052 | provide the necessary information. |
---|
2053 | </li> |
---|
2054 | |
---|
2055 | <li>When a tau pair comes from a massless photon, in dipole shower |
---|
2056 | evolution, for the decay description the mother photon is reassigned |
---|
2057 | to have the sum of the tau momenta.</li> |
---|
2058 | |
---|
2059 | <li>Minor change in initialization sequence for user hooks, |
---|
2060 | to allow for more flexibility.</li> |
---|
2061 | |
---|
2062 | <li>Do not print warnings when multiparton interaction weights are |
---|
2063 | only slightly above unity.</li> |
---|
2064 | |
---|
2065 | <li>Do not write warnings for three known particles that are so close |
---|
2066 | to threshold that widths are switched off to avoid trouble.</li> |
---|
2067 | |
---|
2068 | <li>Some minor typographical changes.</li> |
---|
2069 | |
---|
2070 | </ul> |
---|
2071 | </li> |
---|
2072 | </ul> |
---|
2073 | |
---|
2074 | </chapter> |
---|
2075 | |
---|
2076 | <!-- Copyright (C) 2012 Torbjorn Sjostrand --> |
---|