// main14.cc is a part of the PYTHIA event generator. // Copyright (C) 2012 Torbjorn Sjostrand. // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. // Please respect the MCnet Guidelines, see GUIDELINES for details. // Comparison with some PYTHIA 6.413 cross sections process by process. // Several processes have been left out to keep reasonable execution time. // Some processes are not handled absolutely identically, so minor // systematic differences may occur in addition to the statistical ones. // (For some MSSM Higgs processes 6.413 has been modified to use // running quark masses in loops, like 8.1, to allow proper comparison.) // Subruns 0 - 5 : QCD jets // 6 - 10 : prompt photons. // 11 - 12 : t-channel gamma/Z/W exchange. // 13 - 23 : gamma*/Z^0/W^+-, singly, in pairs or with parton // 24 - 25 : onia. // 26 - 30 : top. // 31 - 40 : Standard Model Higgs. // 41 - 45 : MSSM Higgses (trivial couplings). // 46 - 47 : Z' and W' // 48 - 51 : Left-right-symmetric scenario. // 52 - 52 : Leptoquark. // 53 - 55 : Excited fermions (compositeness). // 56 - 56 : excited Graviton (RS extra dimensions). #include "Pythia.h" using namespace Pythia8; int main() { // First and last process to test: can run from 0 through 40. int iFirst = 0; int iLast = 56; // Statistics. Pythia6 run was with 10000, so no point to use more. int nEvent = 10000; // Normally one subprocess word per subrun, but exceptions exist. int nSub[100]; for (int i = 0; i < 100; ++i) nSub[i] = 1; nSub[1] = 3; nSub[5] = 3; // Starting positions in subprocess words list, recursively defined. int iBeg[101] = { 0 }; for (int i = 0; i < 100; ++i) iBeg[i + 1] = iBeg[i] + nSub[i]; // List of subprocess words. string processes[61] = { "HardQCD:gg2gg", "HardQCD:gg2qqbar", "HardQCD:gg2ccbar", "HardQCD:gg2bbbar","HardQCD:qg2qg" , "HardQCD:qq2qq", "HardQCD:qqbar2gg", "HardQCD:qqbar2qqbarNew", "HardQCD:qqbar2ccbar", "HardQCD:qqbar2bbbar", "PromptPhoton:qg2qgamma", "PromptPhoton:qqbar2ggamma", "PromptPhoton:gg2ggamma", "PromptPhoton:ffbar2gammagamma", "PromptPhoton:gg2gammagamma", "WeakBosonExchange:ff2ff(t:gmZ)", "WeakBosonExchange:ff2ff(t:W)", "WeakSingleBoson:ffbar2gmZ", "WeakSingleBoson:ffbar2W", "WeakDoubleBoson:ffbar2gmZgmZ", "WeakDoubleBoson:ffbar2ZW", "WeakDoubleBoson:ffbar2WW", "WeakBosonAndParton:qqbar2gmZg", "WeakBosonAndParton:qg2gmZq", "WeakBosonAndParton:ffbar2gmZgm", "WeakBosonAndParton:qqbar2Wg", "WeakBosonAndParton:qg2Wq", "WeakBosonAndParton:ffbar2Wgm", "Charmonium:all", "Bottomonium:all", "Top:gg2ttbar", "Top:qqbar2ttbar", "Top:qq2tq(t:W)", "Top:ffbar2ttbar(s:gmZ)", "Top:ffbar2tqbar(s:W)", "HiggsSM:ffbar2H", "HiggsSM:gg2H", "HiggsSM:ffbar2HZ", "HiggsSM:ffbar2HW", "HiggsSM:ff2Hff(t:ZZ)", "HiggsSM:ff2Hff(t:WW)", "HiggsSM:qg2Hq", "HiggsSM:gg2Hg(l:t)", "HiggsSM:qg2Hq(l:t)", "HiggsSM:qqbar2Hg(l:t)", "HiggsBSM:allH1", "HiggsBSM:allH2", "HiggsBSM:allA3", "HiggsBSM:allH+-", "HiggsBSM:allHpair", "NewGaugeBoson:ffbar2gmZZprime", "NewGaugeBoson:ffbar2Wprime", "LeftRightSymmmetry:ffbar2ZR", "LeftRightSymmmetry:ffbar2WR", "LeftRightSymmmetry:ffbar2HLHL", "LeftRightSymmmetry:ffbar2HRHR", "LeptoQuark:all", "ExcitedFermion:dg2dStar", "ExcitedFermion:qq2dStarq", "ExcitedFermion:qqbar2eStare", "ExtraDimensionsG*:all" }; // List of cross sections from Pythia6. double sigma6[57] = { 4.960e-01, 1.627e-02, 2.790e-01, 2.800e-02, 3.310e-04, 3.653e-04, 1.697e-04, 1.163e-05, 1.065e-07, 8.259e-08, 8.237e-08, 2.544e-05, 5.321e-06, 5.571e-05, 1.621e-04, 9.039e-09, 2.247e-08, 5.893e-08, 3.781e-06, 1.078e-05, 4.551e-08, 1.025e-05, 3.208e-05, 5.435e-08, 1.038e-04, 3.929e-05, 4.155e-07, 6.685e-08, 1.898e-07, 4.240e-10, 7.142e-09, 1.547e-10, 7.064e-09, 1.316e-10, 2.332e-10, 5.105e-10, 1.316e-09, 4.462e-11, 5.557e-09, 1.966e-09, 8.725e-12, 2.450e-08, 5.839e-09, 1.687e-08, 8.950e-11, 4.188e-11, 1.980e-07, 4.551e-07, 6.005e-09, 1.102e-07, 7.784e-11, 3.488e-11, 6.006e-08, 3.235e-06, 1.689e-05, 5.986e-07, 3.241e-10 }; // Generator. Pythia pythia; // Standard set of masses for comparison with Fortran code. pythia.readString("5:m0 = 4.2"); pythia.readString("6:m0 = 175."); pythia.readString("23:m0 = 91.2"); pythia.readString("24:m0 = 80."); // Same kinematics cuts as Fortran code. pythia.readString("PhaseSpace:pTHatMin = 20."); pythia.readString("6:mMin = 20."); pythia.readString("23:mMin = 20."); pythia.readString("24:mMin = 20."); pythia.readString("25:mMin = 20."); pythia.readString("32:mMin = 400."); pythia.readString("34:mMin = 400."); pythia.readString("42:mMin = 50."); pythia.readString("5000039:mMin = 50."); // Also same renormalization and factorization scale. pythia.readString("SigmaProcess:renormScale2 = 3"); pythia.readString("SigmaProcess:factorScale2 = 3"); // Switch off unnecessary parts. pythia.readString("PartonLevel:all = off"); pythia.readString("ProcessLevel:resonanceDecays = off"); // No printing of settings, particle data or events. pythia.readString("Init:showProcesses = off"); pythia.readString("Init:showChangedSettings = off"); pythia.readString("Init:showChangedParticleData = off"); pythia.readString("Next:numberCount = 0"); pythia.readString("Next:numberShowInfo = 0"); pythia.readString("Next:numberShowProcess = 0"); pythia.readString("Next:numberShowEvent = 0"); // Debug: show information on cross section maximum and violation. //pythia.readString("PhaseSpace:showSearch = on"); //pythia.readString("PhaseSpace:showViolation = on"); // Loop over processes. for (int iProc = iFirst; iProc <= iLast; ++iProc) { cout << "\n Begin subrun number " << iProc << " : "; // Switch off previous process(es) and switch on new one(s). if (iProc > iFirst) for (int i = iBeg[iProc - 1]; i < iBeg[iProc]; ++i) pythia.readString( processes[i] + " = off" ); for (int i = iBeg[iProc]; i < iBeg[iProc + 1]; ++i) { pythia.readString( processes[i] + " = on" ); if (i > iBeg[iProc]) cout << " + "; cout << processes[i]; } cout << endl; // Switch between SM and MSSM Higgs scenario. if (iProc <= 40) { pythia.readString("Higgs:useBSM = off"); pythia.readString("25:m0 = 200."); } else { pythia.readString("Higgs:useBSM = on"); pythia.readString("25:m0 = 115."); pythia.readString("35:m0 = 300."); pythia.readString("36:m0 = 300."); pythia.readString("37:m0 = 320."); } // Initialize for LHC. pythia.readString("Beams:eCM = 14000."); pythia.init(); // Debug: show initialized resonance data first time around. //if (iProc == iFirst) pythia.particleData.listChanged(true); // Generate events to get cross section statistics. for (int iEvent = 0; iEvent < nEvent; ++iEvent) pythia.next(); // Show statistics. //pythia.stat(); double sigma = pythia.info.sigmaGen(); cout << " Cross section is " << scientific << setprecision(3) << sigma << " and in Pythia6 was " << sigma6[iProc] << ",\n i.e. now is factor >>> " << fixed << sigma / sigma6[iProc] << " <<< different" <