/usr/share/pythia8-examples/examples/main09.cc is in pythia8-examples 8.1.86-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | // main09.cc is a part of the PYTHIA event generator.
// Copyright (C) 2014 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.
// Generate a predetermined second hard interaction.
#include "Pythia8/Pythia.h"
using namespace Pythia8;
int main() {
// Generator.
Pythia pythia;
Event& event = pythia.event;
// Select first hard process (just a small sample of possibilities).
//pythia.readString("HardQCD:all = on");
pythia.readString("Top:all = on");
//pythia.readString("WeakSingleBoson:ffbar2gmZ = on");
//pythia.readString("WeakSingleBoson:ffbar2W = on");
// Select second hard process (complete list of options).
pythia.readString("SecondHard:generate = on");
//pythia.readString("SecondHard:TwoJets = on");
pythia.readString("SecondHard:PhotonAndJet = on");
//pythia.readString("SecondHard:TwoPhotons = on");
//pythia.readString("SecondHard:SingleGmZ = on");
//pythia.readString("SecondHard:SingleW = on");
//pythia.readString("SecondHard:TwoBJets = on");
// Kinematics cuts, common for the two.
pythia.readString("PhaseSpace:mHatMin = 40.");
pythia.readString("PhaseSpace:pTHatMin = 20.");
// Initialize for LHC at 8 TeV.
pythia.readString("Beams:eCM = 8000.");
pythia.init();
// Histogram.
Hist pTfirst("pT first collision", 100, 0., 400.);
Hist pTsecond("pT second collision", 100, 0., 200.);
Hist pTdiff("pT first-second collision", 100, -100., 300.);
Hist nMult("number of multiparton interactions", 100, -0.5, 99.5);
Hist bMore("b enhancement factor", 100, 0., 10.);
Hist nChg("charged multiplicity", 100, -0.5, 999.5);
// Generate events.
for (int iev = 0; iev < 1000; ++iev) {
pythia.next();
// Histogram pT.
double pT1 = pythia.info.pTMPI(0);
double pT2 = pythia.info.pTMPI(1);
pTfirst.fill( pT1 );
pTsecond.fill( pT2 );
pTdiff.fill( pT1 - pT2 );
// Histogram multiparton interactions
double nMPI = pythia.info.nMPI();
nMult.fill( nMPI );
bMore.fill( pythia.info.enhanceMPI() );
// Histogram charged multiplicity.
int nCharged = 0;
for (int i = 0; i < event.size(); ++i)
if (event[i].isFinal() && event[i].isCharged()) ++nCharged;
nChg.fill( nCharged );
}
// Compare full statistics listing with what is set in info.
pythia.stat();
cout << scientific << setprecision(3) << "\n From pythia.info: sigma = "
<< pythia.info.sigmaGen() << " +- " << pythia.info.sigmaErr()
<< endl;
// Print histograms.
cout << pTfirst << pTsecond << pTdiff << nMult << bMore << nChg;
// Done.
return 0;
}
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