PHPy6ParticleTrigger.C

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#include "PHPy6GenTrigger.h"
#include "PHPy6ParticleTrigger.h"
#include <phool/PHCompositeNode.h>
#include <phool/phool.h>
#include <phool/getClass.h>

#include <phhepmc/PHHepMCGenEvent.h>
#include <HepMC/GenEvent.h>

#include <cstdlib>
#include <iostream>
using namespace std;

//___________________________________________________________________________
PHPy6ParticleTrigger::PHPy6ParticleTrigger(const std::string &name):
  PHPy6GenTrigger(name),

  _theParticleType(0),
  _Q2Min(0.0),

  _doTheParticleType(false),
  _doQ2Min(false)
{}


bool PHPy6ParticleTrigger::Apply( const HepMC::GenEvent* evt )
{

  if(_doQ2Min && evt->pdf_info()->scalePDF() < _Q2Min) return false;
  //  cout<<"EVENT"<<endl;
  /*  
  for ( HepMC::GenEvent::particle_const_iterator p
          = evt->particles_begin(); p != evt->particles_end(); ++p ){
    if((*p)->status()==1) cout<<(*p)->pdg_id()<<" "<<(*p)->momentum().eta()<<" "<<sqrt(pow((*p)->momentum().px(),2) + pow((*p)->momentum().py(),2))<<endl;
                                                                                   
  }
  */
  if(!_doTheParticleType) return true;

  // Loop over all particles in the event
  for ( HepMC::GenEvent::particle_const_iterator p
          = evt->particles_begin(); p != evt->particles_end(); ++p ){
  
    int pi_num = 0;  

    if((*p)->pdg_id() != _theParticleType) continue;
    
    //if((*p)->pdg_id() == _theParticleType) return true;

    
    for ( HepMC::GenVertex::particle_iterator decay
            = (*p)->end_vertex()->
            particles_begin(HepMC::children);
          decay != (*p)->end_vertex()->
            particles_end(HepMC::children);
          ++decay )
      {
        // check if particle decays further 
        if(!(*decay)->end_vertex()){
          if(abs((*decay)->pdg_id()) == 211) pi_num++;
        }
        
        // loop over decay if particle decays further 
        else if((*decay)->end_vertex()){
          
          //further decay loop /
          for ( HepMC::GenVertex::particle_iterator second_decay
                  = (*decay)->end_vertex()->
                  particles_begin(HepMC::children);
                second_decay != (*decay)->end_vertex()->
                  particles_end(HepMC::children);
                ++second_decay )
            {
              if (abs((*second_decay)->pdg_id()) == 211) pi_num++;
              
              if ((*second_decay)->status() != 1){
                for ( HepMC::GenVertex::particle_iterator third_decay
                        = (*second_decay)->end_vertex()->
                        particles_begin(HepMC::children);
                      third_decay != (*second_decay)->end_vertex()->
                        particles_end(HepMC::children);
                      ++third_decay )
                  {
                    if(abs((*third_decay)->pdg_id()) == 211) pi_num++;
                  }
              }
            }
        }
      }
    
    if (pi_num == 3) return true;
    
  }//pythia event for loop

return false;

}

void PHPy6ParticleTrigger::SetParticleType(int pid) {
  _theParticleType = pid;
  _doTheParticleType = true;
}

void PHPy6ParticleTrigger::SetQ2Min(double Q2) {
  _Q2Min = Q2;
  _doQ2Min = true;
}