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| 3 | <title>Sample Main Programs</title> |
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| 28 | <form method='post' action='SampleMainPrograms.php'> |
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| 29 | |
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| 30 | <h2>Sample Main Programs</h2> |
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| 31 | |
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| 32 | Descriptions of available classes, methods and settings are all |
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| 33 | very good and useful. Ultimately they are necessary for you to |
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| 34 | be able to fine-tune your runs to the task at hand. To get going, |
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| 35 | however, nothing helps like having explicit examples to study. |
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| 36 | This is what is provided in the <code>examples</code> subdirectory, |
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| 37 | along with instructions how they should be run: |
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| 38 | <ul> |
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| 39 | |
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| 40 | <li><code>main00.cc</code> : does not exist, but it has been defined |
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| 41 | in the <code>Makefile</code>, so this name could be used for a simple |
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| 42 | first test run. |
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| 43 | |
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| 44 | <li><code>main01.cc</code> : a simple study of the charged multiplicity |
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| 45 | for jet events at the LHC. (Brief example fitting on one slide.)</li> |
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| 46 | |
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| 47 | <li><code>main02.cc</code> : a simple study of the <i>pT</i> spectrum |
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| 48 | of Z bosons at the Tevatron. (Brief example fitting on one slide.)</li> |
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| 49 | |
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| 50 | <li><code>main03.cc</code> : a simple study of several different kinds |
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| 51 | of events, with the choice to be made in the <code>main03.cmnd</code> |
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| 52 | "cards file".</li> |
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| 53 | |
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| 54 | <li><code>main04.cc</code> : tests of cross sections, multiplicities and |
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| 55 | average transverse momenta for elastic, diffractive and nondiffractive |
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| 56 | topologies, using <code>main04.cmnd</code> to pick processes.</li> |
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| 57 | |
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| 58 | <li><code>main05.cc</code> : generation of QCD jet events at the LHC, |
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| 59 | with jet analysis using the <code>SlowJet</code> inclusive anti-<i>kT</i> |
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| 60 | sequential-recombination finder and the <code>CellJet</code> |
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| 61 | cone-jet finder.</li> |
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| 62 | |
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| 63 | <li><code>main06.cc</code> : generation of LEP1 hadronic events, i.e. |
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| 64 | <i>e^+e^- -> gamma*/Z^0 -> q qbar</i>, with charged multiplicity, |
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| 65 | sphericity, thrust and jet analysis.</li> |
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| 66 | |
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| 67 | <li><code>main07.cc</code> : set up a fictitious production process |
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| 68 | to a generic resonance, where you easily can compose your own list |
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| 69 | of (two-body) decay modes to a variety of final states. Also traces |
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| 70 | decay chains down to truly stable particles: gamma, e+-, p/pbar and |
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| 71 | neutrinos. Suitable for astroparticle applications, like neutralino |
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| 72 | pair annihilation, where cross sections are calculated separately |
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| 73 | in another program.</li> |
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| 74 | |
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| 75 | <li><code>main08.cc</code> : generation of the QCD jet cross section |
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| 76 | biased towards higher pT values, by two different techniques. |
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| 77 | Firstly, by splitting the run into subruns, each in its own <i>pT</i> |
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| 78 | bin, and adding the results properly reweighted. Two suboptions, with |
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| 79 | limits set either in the main program or by subrun specification in the |
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| 80 | <code>main08.cmnd</code> file. Secondly, by a continuous reweighting |
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| 81 | with a <i>pT^4</i> bias in the selection, compensated by a |
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| 82 | <i>1/pT^4</i> event weight. Also inclusion of soft processes is |
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| 83 | illustrated, with subruns and weighted events.</li> |
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| 84 | |
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| 85 | <li><code>main09.cc</code> : generation of two predetermined hard |
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| 86 | interactions in each event.</li> |
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| 87 | |
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| 88 | <li><code>main10.cc</code> : illustration how userHooks can be used |
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| 89 | interact directly with the event-generation process.</li> |
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| 90 | |
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| 91 | <li><code>main11.cc</code> : a study of top events, fed in from the |
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| 92 | Les Houches Event File <code>ttbar.lhe</code>, here generated by |
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| 93 | PYTHIA 6.4. This file currently only contains 100 events |
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| 94 | so as not to make the distributed PYTHIA package too big, and so serves |
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| 95 | mainly as a demonstration of the principles involved. </li> |
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| 96 | |
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| 97 | <li><code>main12.cc</code> : a more sophisticated variant of |
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| 98 | <code>main11.cc</code>, where two Les Houches Event Files |
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| 99 | (<code>ttbar.lhe</code> and <code>ttbar2.lhe</code>) successively |
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| 100 | are used as input. Also illustrating some other aspects, like the |
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| 101 | capability to mix in internally generated events.</li> |
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| 102 | |
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| 103 | <li><code>main13.cc</code> : a streamlined version of |
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| 104 | <code>main12.cc</code>, where two Les Houches Event Files |
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| 105 | (<code>ttbar.lhe</code> and <code>ttbar2.lhe</code>) successively |
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| 106 | are used as input in <code>main13.cmnd</code> file.</li> |
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| 107 | |
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| 108 | <li><code>main14.cc</code> : a systematic comparison of several |
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| 109 | cross section values with their corresponding values in PYTHIA 6.4, |
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| 110 | the latter available as a table in the code.</li> |
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| 111 | |
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| 112 | <li><code>main15.cc</code> : loop over several tries, either to redo |
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| 113 | B decays only or to redo the complete hadronization chain of an event. |
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| 114 | Since much of the generation process is only made once this is a way |
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| 115 | to increase efficiency.</li> |
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| 116 | |
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| 117 | <li><code>main16.cc</code> : put all user analysis code into a class |
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| 118 | of its own, separate from the main program; provide the "cards file" |
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| 119 | name as a command-line argument.</li> |
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| 120 | |
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| 121 | <li><code>main17.cc</code> : shows (a) how to use UserHooks to |
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| 122 | regularize onium cross section for pT -> 0, and (b) how decays |
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| 123 | could be handled externally.</li> |
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| 124 | |
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| 125 | <li><code>main18.cc</code> : shows how to write an event filter class, |
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| 126 | where you keep a vector of pointers to the subset of particles you |
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| 127 | want to study further. The event record itself remains unchanged.</li> |
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| 128 | |
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| 129 | <li><code>main19.cc</code> : use several instances of Pythia, one for |
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| 130 | signal events and others for a variable number of pileup and "beam-gas" |
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| 131 | events, combined into one common event record.</li> |
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| 132 | |
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| 133 | <li><code>main20.cc</code> : shows how PYTHIA 8 can write a Les Houches |
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| 134 | Event File, using facilities potentially useful also for other programs |
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| 135 | to write an LHEF.</li> |
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| 136 | |
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| 137 | <li><code>main21.cc</code> : an example how a single particle or various |
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| 138 | parton-level configurations can be input directly for hadronization, |
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| 139 | without being tied to the full process-generation machinery, e.g. to |
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| 140 | study the hadronization of junction topologies. Can also be used for |
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| 141 | single-resonance decays, with showers.</li> |
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| 142 | |
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| 143 | <li><code>main22.cc</code> : shows how an external resonance can be |
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| 144 | implemented as a new class derived from a PYTHIA base class, and be |
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| 145 | used in an external process, both of them handed in for generation |
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| 146 | as with normal internal classes.</li> |
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| 147 | |
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| 148 | <li><code>main23.cc</code> : shows how an external beam momentum spread |
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| 149 | and vertex location generator can be implemented as a new class derived |
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| 150 | from a PYTHIA base class, and then handed in for internal use. |
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| 151 | Also how to use an external random-number generator and an external |
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| 152 | parton distribution set.</li> |
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| 153 | |
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| 154 | <li><code>main24.cc</code> : tests of internally implemented cross sections |
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| 155 | for Supersymmetric particle production, with SYSY spectrum defined in |
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| 156 | <code>cmssm.spc</code> and settings in <code>main24.cmnd</code>. For |
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| 157 | illustration, an alternative example spectrum is also |
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| 158 | available, <code>sps1aWithDecays.spc</code>, which contains a decay |
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| 159 | table in SLHA format.</li> |
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| 160 | |
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| 161 | <li><code>main25.cc</code> : input RPV-SUSY events from an LHEF file that |
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| 162 | contains an SLHA spectrum inside its header. The event file, |
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| 163 | <code>main25.lhe</code>, contains a sample events that |
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| 164 | illustrate how to arrange color tags in the presence of the |
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| 165 | color-space epsilon tensors that accompany baryon number violating |
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| 166 | event topologies. </li> |
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| 167 | |
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| 168 | <li><code>main26.cc</code> : test program for processes in scenarios |
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| 169 | with large extra dimensions or unparticles. </li> |
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| 170 | |
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| 171 | <li><code>main27.cc</code> : production of Kaluza-Klein <i>gamma/Z</i> |
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| 172 | states in TeV-sized extra dimensions. </li> |
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| 173 | |
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| 174 | <li><code>main28.cc</code> : production of long-lived R-hadrons, that |
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| 175 | are forced to decay at a separate vertices and possibly with changed |
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| 176 | momenta.</li> |
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| 177 | |
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| 178 | <li><code>main31.cc</code> : exemplifies an improved matching of |
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| 179 | parton showers to LHEF-style input based on the POWHEG approach. |
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| 180 | The <code>main31.cmnd</code> allows to switch between several |
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| 181 | different matching options. It also allows to select input process, |
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| 182 | in this case either for the POWHEG-hvq program applied to top |
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| 183 | pair production [<a href="Bibliography.php" target="page">Cor10</a>] or for QCD 2+3-jet events. The small |
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| 184 | samples of input events are stored in the <code>powheg-hvq.lhe</code> |
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| 185 | and <code>powheg-dijets.lhe</code> files, respectively. |
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| 186 | </li> |
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| 187 | |
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| 188 | <li><code>main32.cc</code> : exemplifies MLM merging for ALPGEN events, |
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| 189 | see <?php $filepath = $_GET["filepath"]; |
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| 190 | echo "<a href='AlpgenAndMLM.php?filepath=".$filepath."' target='page'>";?>ALPGEN and MLM merging</a> for further |
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| 191 | details. Traditionally the ALPGEN output is split into one file with |
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| 192 | events and another with parameters and cross sections (unlike in LHEF). |
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| 193 | Here a sample of <i>W + 3 jets</i> events is stored in |
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| 194 | <code>main32.unw</code> and the parameters to go with it in |
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| 195 | <code>main32_unw.par</code>, while normal PYTHIA control cards are in |
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| 196 | <code>main32.cmnd</code>. |
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| 197 | </li> |
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| 198 | |
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| 199 | <li><code>main41.cc</code> : similar to <code>main01</code>, except that |
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| 200 | the event record is output in the HepMC event record format. Requires that |
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| 201 | HepMC is properly linked. Note that the <code>hepmcout41.dat</code> output |
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| 202 | file can become quite big; so no example is included in this |
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| 203 | distribution.</li> |
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| 204 | |
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| 205 | <li><code>main42.cc</code> : a streamlined version for the generation |
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| 206 | of events that are then stored in HepMC format, without any event |
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| 207 | analysis. That is, all physics studies will have to be done afterwards. |
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| 208 | The name of the input "cards file" (e.g. <code>main42.cmnd</code>) |
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| 209 | and output HepMC event file (e.g. <code>hepmcout42.dat</code>) are to |
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| 210 | be provided as command-line arguments. Requires that HepMC is properly |
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| 211 | linked. Note that the HepMC output file can become quite big; so no |
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| 212 | example is included in this distribution.</li> |
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| 213 | |
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| 214 | <li><code>main51.cc</code> : a test of the shape of parton densities, |
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| 215 | as a check prior to using a given PDF set in a generator. Requires |
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| 216 | that LHAPDF is properly linked.</li> |
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| 217 | |
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| 218 | <li><code>main52.cc</code> : compares the charged multiplicity |
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| 219 | distribution, and a few other minimum-bias physics aspects, between |
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| 220 | default PYTHIA PDF and another one. Requires that LHAPDF is properly |
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| 221 | linked.</li> |
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| 222 | |
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| 223 | <li><code>main53.cc</code> : tests the possibility to do backwards |
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| 224 | evolution from an incoming photon at the hard interaction. Requires |
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| 225 | that you link to a LHAPDF set that includes the photon PDF.</li> |
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| 226 | |
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| 227 | <li><code>main61.cc</code> : a streamlined version for the generation |
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| 228 | of events that are then stored in HepMC format, without any event |
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| 229 | analysis. That is, just like <code>main42.cc</code>, with the difference |
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| 230 | that <code>main61.cc</code> can be used in conjunction with LHAPDF. |
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| 231 | The name of the input "cards file" (e.g. <code>main61.cmnd</code>) |
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| 232 | and output HepMC event file (e.g. <code>hepmcout61.dat</code>) are to |
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| 233 | be provided as command-line arguments. Requires that HepMC and LHAPDF |
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| 234 | are properly linked. Note that the HepMC output file can become quite |
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| 235 | big; so no example is included in this distribution.</li> |
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| 236 | |
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| 237 | <li><code>main62.cc</code> : a further extension of <code>main61.cc</code>, |
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| 238 | where subruns are used to process several consecutive LHEF, |
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| 239 | as in <code>main13.cc</code>, with information stored e.g in |
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| 240 | <code>main62.cmnd</code>. Other comments as for <code>main61.cc</code>.</li> |
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| 241 | |
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| 242 | <li><code>main71.cc</code> : an example how the FastJet jet finding |
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| 243 | package can be linked to allow an analysis of the final state, |
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| 244 | in this case for a study of W + jet production.</li> |
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| 245 | |
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| 246 | <li><code>main72.cc</code> : a comparison of SlowJet and FastJet |
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| 247 | jet finding, showing that they find the same jets if run under |
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| 248 | identical conditions, in this case for QCD jets.</li> |
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| 249 | |
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| 250 | <li><code>main81.cc</code> : do CKKW-L merging with a merging scale |
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| 251 | defined in <i>kT</i>. Input is provided by the <code>main81.cmnd</code> |
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| 252 | file and the three data files <code>w+_production_lhc_0.lhe</code>, |
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| 253 | <code>w+_production_lhc_1.lhe</code> and <code>w+_production_lhc_2.lhe</code>. |
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| 254 | </li> |
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| 255 | |
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| 256 | <li><code>main82.cc</code> : do CKKW-L merging with a user-defined |
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| 257 | merging scale function. Input is provided by the <code>main82.cmnd</code> |
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| 258 | file and the three data files <code>w+_production_lhc_0.lhe</code>, |
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| 259 | <code>w+_production_lhc_1.lhe</code> and <code>w+_production_lhc_2.lhe</code>. |
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| 260 | </li> |
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| 261 | |
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| 262 | <li><code>main83.cc</code> : as <code>main82.cc</code> but with an |
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| 263 | additional cut on the lowest multiplicity allowed for the reclustered |
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| 264 | state. The same input as for <code>main82.cc</code> can be used. |
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| 265 | </li> |
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| 266 | |
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| 267 | <li><code>main84.cc</code> : do CKKW-L merging with output in such a way |
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| 268 | that it can be used in subsequent RIVET analyses. Input is provided by |
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| 269 | the <code>main84.cmnd</code> file and the three data files |
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| 270 | <code>w+_production_lhc_0.lhe</code>, <code>w+_production_lhc_1.lhe</code> |
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| 271 | and <code>w+_production_lhc_2.lhe</code>. |
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| 272 | </li> |
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| 273 | |
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| 274 | <li><code>main91.cc</code> : exemplifies how you can link in runtime |
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| 275 | generation of hard processes from PYTHIA 6, using the Les Houches |
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| 276 | Accord facilities. This example is deprecated, since PYTHIA 8 by now |
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| 277 | contains essentially all hard processes found in PYTHIA 6.</li> |
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| 278 | |
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| 279 | </ul> |
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| 280 | |
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| 281 | In addition two main program illustrating the use of ROOT are available |
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| 282 | in the <code>rootexamples</code> subdirectory: |
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| 283 | |
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| 284 | <ul> |
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| 285 | |
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| 286 | <li><code>hist.cc</code> : shows how ROOT can be used for histogramming |
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| 287 | in a program that for the rest is structured like a normal PYTHIA run. |
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| 288 | </li> |
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| 289 | |
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| 290 | <li><code>tree.cc</code> : shows how PYTHIA events can be stored as |
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| 291 | ROOT trees.</li> |
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| 292 | |
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| 293 | </ul> |
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| 294 | |
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| 295 | This subdirectory also contains a special Makefile and related |
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| 296 | documentation. |
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| 297 | |
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| 298 | |
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| 299 | </body> |
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| 300 | </html> |
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| 301 | |
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| 302 | <!-- Copyright (C) 2012 Torbjorn Sjostrand --> |
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