1 | // main03.cc is a part of the PYTHIA event generator. |
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2 | // Copyright (C) 2012 Torbjorn Sjostrand. |
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3 | // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. |
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4 | // Please respect the MCnet Guidelines, see GUIDELINES for details. |
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5 | |
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6 | // This is a simple test program. |
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7 | // It illustrates how different processes can be selected and studied. |
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8 | // All input is specified in the main03.cmnd file. |
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9 | |
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10 | #include "Pythia.h" |
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11 | |
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12 | using namespace Pythia8; |
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13 | |
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14 | int main() { |
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15 | |
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16 | // Generator. |
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17 | Pythia pythia; |
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18 | |
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19 | // Shorthand for the event record in pythia. |
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20 | Event& event = pythia.event; |
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21 | |
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22 | // Read in commands from external file. |
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23 | pythia.readFile("main03.cmnd"); |
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24 | |
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25 | // Extract settings to be used in the main program. |
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26 | int nEvent = pythia.mode("Main:numberOfEvents"); |
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27 | int nAbort = pythia.mode("Main:timesAllowErrors"); |
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28 | |
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29 | // Initialize. |
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30 | pythia.init(); |
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31 | |
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32 | // Book histograms. |
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33 | Hist pThard("process pT scale", 100, 0., 500.); |
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34 | Hist nFinal("final particle multiplicity", 100, -0.5, 1599.5); |
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35 | Hist nCharged("charged particle multiplicity", 100, -0.5, 799.5); |
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36 | Hist dndy("dn/dy for charged particles", 100, -10., 10.); |
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37 | Hist dndeta("dn/d(eta) for charged particles", 100, -10., 10.); |
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38 | Hist dndpT("dn/dpT for charged particles", 100, 0., 10.); |
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39 | Hist epCons("deviation from energy-momentum conservation", 100, 0., 1e-6); |
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40 | |
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41 | // Begin event loop. |
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42 | int iAbort = 0; |
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43 | for (int iEvent = 0; iEvent < nEvent; ++iEvent) { |
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44 | |
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45 | // Generate events. Quit if many failures. |
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46 | if (!pythia.next()) { |
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47 | if (++iAbort < nAbort) continue; |
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48 | cout << " Event generation aborted prematurely, owing to error!\n"; |
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49 | break; |
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50 | } |
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51 | |
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52 | // Fill hard scale of event. |
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53 | pThard.fill( pythia.info.pTHat() ); |
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54 | |
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55 | // Loop over final particles in the event. |
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56 | int nFin = 0; |
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57 | int nChg = 0; |
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58 | Vec4 pSum; |
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59 | for (int i = 0; i < event.size(); ++i) if (event[i].isFinal()) { |
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60 | |
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61 | // Analyze all particles. |
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62 | nFin++; |
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63 | pSum += event[i].p(); |
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64 | |
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65 | // Analyze charged particles and fill histograms. |
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66 | if (event[i].isCharged()) { |
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67 | ++nChg; |
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68 | dndy.fill( event[i].y() ); |
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69 | dndeta.fill( event[i].eta() ); |
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70 | dndpT.fill( event[i].pT() ); |
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71 | } |
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72 | |
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73 | // End of particle loop. Fill global properties. |
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74 | } |
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75 | nFinal.fill( nFin ); |
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76 | nCharged.fill( nChg ); |
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77 | pSum /= event[0].e(); |
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78 | double epDev = abs(pSum.e() - 1.) + abs(pSum.px()) + abs(pSum.py()) |
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79 | + abs(pSum.pz()); |
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80 | epCons.fill(epDev); |
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81 | |
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82 | // End of event loop. |
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83 | } |
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84 | |
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85 | // Final statistics. Normalize and output histograms. |
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86 | pythia.stat(); |
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87 | dndy *= 5. / nEvent; |
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88 | dndeta *= 5. / nEvent; |
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89 | dndpT *= 10. / nEvent; |
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90 | cout << pThard << nFinal << nCharged << dndy << dndeta << dndpT << epCons; |
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91 | |
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92 | // Done. |
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93 | return 0; |
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94 | } |
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