EvtPycont.cc

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 1998      Caltech, UCSB
//
// Module: EvtPycont.cc
//
// Description: Routine to generate e+e- --> q\barq  via Jetset
//
// Modification history:
//
//    PCK     August 4, 1997        Module created
//    RS      October 28, 2002      copied from EvtJscont.cc
//
//------------------------------------------------------------------------
//
#include "EvtPycont.hh"
#include "../EvtGenBase/EvtDecayTable.hh"
#include "../EvtGenBase/EvtGlobalSet.hh"
#include "../EvtGenBase/EvtId.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "EvtPythia.hh"
#include <iostream>
#include <stdlib.h>
#include <string>
using std::endl;
 
// common/CBBEAM/MAXIMUM
extern "C" struct {
  double maximum;
} cbbeam_;
 
// COMMON/ISRFLAG/myisr
extern "C" struct {
  int myisr;
} isrflag_;
 
extern "C" struct {
  int    mint[400];
  double vint[400];
} pyint1_;
 
extern "C" struct {
  int    mstp[200];
  double parp[200]; // parp(2) is the lowers energy allowed by pythia
  int    msti[200];
  double pari[200];
} pypars_;
 
extern "C" {
extern void pystat_( int& );
}
 
extern "C" struct {
  int dc[18];
} decaych_;
 
extern "C" {
extern void initpythia_( int* );
}
 
EvtPycont::~EvtPycont() {
  //  int i=1;
  //  pystat_(i);
}
 
void EvtPycont::getName( std::string& model_name ) { model_name = "PYCONT"; }
 
EvtDecayBase* EvtPycont::clone() { return new EvtPycont; }
 
void EvtPycont::init() {
  // check that there are 1 argument
  if ( !( getNArg() == 12 || getNArg() == 0 || getNArg() == 1 ) )
  {
    report( ERROR, "EvtGen" )
        << "EvtPYCONT expects "
        << " 12 arguments (d u s c b t e nu_e mu nu_mu tau nu_tau) but found: " << getNArg()
        << endl;
  }
  checkNArg( 0, 1, 12 );
  isrflag_.myisr = 1; // default value, turn on ISR
  for ( int i = 0; i < 18; i++ ) decaych_.dc[i] = 0;
  if ( getNArg() == 12 )
  {
    decaych_.dc[0]  = (int)getArg( 0 );
    decaych_.dc[1]  = (int)getArg( 1 );
    decaych_.dc[2]  = (int)getArg( 2 );
    decaych_.dc[3]  = (int)getArg( 3 );
    decaych_.dc[4]  = (int)getArg( 4 );
    decaych_.dc[5]  = (int)getArg( 5 );
    decaych_.dc[10] = (int)getArg( 6 );
    decaych_.dc[11] = (int)getArg( 7 );
    decaych_.dc[12] = (int)getArg( 8 );
    decaych_.dc[13] = (int)getArg( 9 );
    decaych_.dc[14] = (int)getArg( 10 );
    decaych_.dc[15] = (int)getArg( 11 );
  }
  else if ( getNArg() == 1 )
  {
    isrflag_.myisr = (int)getArg( 0 );
    decaych_.dc[0] = 1;
    decaych_.dc[1] = 1;
    decaych_.dc[2] = 1;
    decaych_.dc[3] = 1;
  }
}
 
void EvtPycont::initProbMax() { noProbMax(); }
 
void EvtPycont::decay( EvtParticle* p ) {
 
  double energy   = p->mass();
  cbbeam_.maximum = energy; // ini. parp(171), see EvtPythia.cc
 
  // std::cout<<"energy= "<<energy<<std::endl;
 
  if ( energy == 0 )
  {
    std::cout << "Particle " << EvtPDL::name( p->getId() ) << " has zero mass" << std::endl;
    abort();
  }
  EvtPythia::pythiaInit( 0 ); // init. for the firt events
  int mydummy = 0;
  initpythia_( &mydummy ); // init. energy event by event
 
  EvtVector4R p4[100];
 
  int   i, more, nson;
  int   ndaugjs;
  int   kf[100];
  EvtId id[100];
  int   type[MAX_DAUG];
 
  double px[100], py[100], pz[100], e[100];
 
  if ( p->getNDaug() != 0 ) { return; }
  do {
    EvtPythia::pythiacont( &energy, &ndaugjs, kf, px, py, pz, e );
 
    double toteng = 0;
 
    for ( i = 0; i < ndaugjs; i++ )
    {
 
      id[i] = EvtPDL::evtIdFromStdHep( kf[i] );
 
      type[i] = EvtPDL::getSpinType( id[i] );
 
      // std::cout<<"i, id[i] "<<i<<" "<<EvtPDL::getStdHep(id[i])<<std::endl;
 
      // have to protect against negative mass^2 for massless particles
      // i.e. neutrinos and photons.
      // this is uggly but I need to fix it right now....
      toteng += e[i];
      if ( px[i] * px[i] + py[i] * py[i] + pz[i] * pz[i] >= e[i] * e[i] )
        e[i] = sqrt( px[i] * px[i] + py[i] * py[i] + pz[i] * pz[i] ) + 0.0000000000001;
 
      p4[i].set( e[i], px[i], py[i], pz[i] );
    }
    // if( fabs(toteng-energy)>0.001 ) std::cout<<"Total energy of pythia decayed particle is
    // larger than parent energy"<<std::endl;
 
    int channel = EvtDecayTable::inChannelList( p->getId(), ndaugjs, id );
 
    more = ( ( channel != -1 ) && ( channel != p->getChannel() ) );
    // std::cout<<"more="<<more<<std::endl;
 
  } while ( more );
 
  p->makeDaughters( ndaugjs, id );
 
  for ( i = 0; i < ndaugjs; i++ ) p->getDaug( i )->init( id[i], p4[i] );
 
  if ( energy < 2.0 ) { EvtGlobalSet::ConExcPythia = 0; }
  else { EvtGlobalSet::ConExcPythia = 1; } // cut off for minimum Mhad
  return;
}