main103
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// main103.cc is a part of the PYTHIA event generator.
// Copyright (C) 2023 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.
// Authors:
// Steve Mrenna
// Keywords:
// Command file
// User hook
// This is a simple test program.
// It illustrates how to filter resonance decay products to obtain a certain
// final state.
// Usage: (this executable) (command-file)
// If no command-file is provided, a default is use.
#include "Pythia8/Pythia.h"
#include "Pythia8Plugins/ResonanceDecayFilterHook.h"
using namespace Pythia8;
//==========================================================================
int main(int argc, char* argv[]) {
// Generator. Shorthand for the event.
Pythia pythia;
auto myUserHooks = make_shared<ResonanceDecayFilterHook>(pythia.settings);
pythia.setUserHooksPtr( myUserHooks);
// Read in commands from external file.
if (argc == 1) {
cout << "Using default command-file main103.cmnd" << endl;
pythia.readFile("main103.cmnd");
} else {
// Check that the provided input name corresponds to an existing file.
ifstream is(argv[1]);
if (!is.good()) {
cerr << " Usage: executable command-file. \n";
cerr << " Command-line file " << argv[1] << " was not found. \n"
<< " Program stopped! " << endl;
return 1;
}
pythia.readFile(argv[1]);
}
// Extract settings to be used in the main program.
int nEvent = pythia.mode("Main:numberOfEvents");
int nAbort = pythia.mode("Main:timesAllowErrors");
// Initialize.
pythia.init();
int iAbort = 0;
for (int iEvent = 0; iEvent < nEvent; ++iEvent) {
// Generate events. Quit if too many failures.
if (!pythia.next()) {
if (++iAbort < nAbort) continue;
cout << " Event generation aborted prematurely, owing to error!\n";
break;
}
// End of event loop.
}
// Final statistics and histograms.
pythia.stat();
double filterEfficiency = (double) pythia.info.getCounter(4)
/ (double) myUserHooks->returnCounter();
ParticleDataEntryPtr particlePtr =
pythia.particleData.particleDataEntryPtr(24);
double br_lepton(0.0);
br_lepton += particlePtr->channel(6).bRatio();
br_lepton += particlePtr->channel(7).bRatio();
br_lepton += particlePtr->channel(8).bRatio();
double exactFilter = 2.0*br_lepton*(1.0-br_lepton);
cout << "ResonanceDecayFilterHook efficiency = " << filterEfficiency << "\n";
cout << "on-shell theoretical efficiency = " << exactFilter << "\n";
// Done.
return 0;
}