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HepMC Reference DocumentationHepMC |
00001 #ifndef PYTHIA_HELPER_H 00002 #define PYTHIA_HELPER_H 00004 // garren@fnal.gov, April 2007 00005 // 00006 // definitions needed by the pythia examples 00007 // 00009 #include "HepMC/PythiaWrapper.h" 00010 #include "HepMC/GenCrossSection.h" 00011 00012 void initPythia(); 00013 00014 00016 inline HepMC::GenCrossSection getPythiaCrossSection() { 00017 00018 HepMC::GenCrossSection xsec; 00019 // xsec(0,2) contains the sum of differential cross sections in mb 00020 // ngen(0,2) contains the combined number of generated events 00021 // convert to pb (HepMC convention) 00022 double xsecval = pyint5.xsec[2][0] * 1.0e9; 00023 // statistical error 00024 double xsecerr = xsecval / std::sqrt( pyint5.ngen[2][0] ); 00025 // set and return cross section information 00026 xsec.set_cross_section(xsecval, xsecerr); 00027 return xsec; 00028 } 00029 00030 #endif // PYTHIA_HELPER_H