PythiaFilterGammaJetIsoPi0.cc

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#include "GeneratorInterface/GenFilters/interface/PythiaFilterGammaJetIsoPi0.h"
#include "SimDataFormats/GeneratorProducts/interface/HepMCProduct.h"
#include "SimGeneral/HepPDTRecord/interface/ParticleDataTable.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/Framework/interface/ESHandle.h"
#include <iostream>
#include<list>
#include<vector>
#include<cmath>

using namespace edm;
using namespace std;

namespace{

  double deltaR2(double eta0, double phi0, double eta, double phi){
    double dphi=phi-phi0;
    if(dphi>M_PI) dphi-=2*M_PI;
    else if(dphi<=-M_PI) dphi+=2*M_PI;
    return dphi*dphi+(eta-eta0)*(eta-eta0);
  }

  double deltaPhi(double phi0, double phi){
    double dphi=phi-phi0;
    if(dphi>M_PI) dphi-=2*M_PI;
    else if(dphi<=-M_PI) dphi+=2*M_PI;
    return dphi;
  }

  class ParticlePtGreater{
  public:
    int operator()(const HepMC::GenParticle * p1, 
           const HepMC::GenParticle * p2) const{
      return p1->momentum().perp() > p2->momentum().perp();
    }
  };
}


PythiaFilterGammaJetIsoPi0::PythiaFilterGammaJetIsoPi0(const edm::ParameterSet& iConfig) :
  label_(iConfig.getUntrackedParameter("moduleLabel",std::string("generator"))),
  etaMin(iConfig.getUntrackedParameter<double>("MinPi0Eta", 1.65)),
  PtMin(iConfig.getUntrackedParameter<double>("MinPi0Pt", 50.)),
  etaMax(iConfig.getUntrackedParameter<double>("MaxPi0Eta", 2.5)),
  PtMax(iConfig.getUntrackedParameter<double>("MaxPi0Pt", 100.)),
  isocone(iConfig.getUntrackedParameter<double>("IsoCone",0.3)),
  isodr(iConfig.getUntrackedParameter<double>("IsoDR",0.5)),
  ebEtaMax(1.479){ 
//
  deltaEB=0.01745/2  *5; // delta_eta, delta_phi
  deltaEE=2.93/317/2 *5; // delta_x/z, delta_y/z
  theNumberOfTestedEvt = 0;
  theNumberOfSelected = 0;

  cout << " Cut Definition: " << endl;
  cout << " MinPi0Pt = " << PtMin << endl;
  cout << " MaxPi0Pt = " << PtMax << endl;
  cout << " MinPi0Eta = " << etaMin << endl;
  cout << " MaxPi0Eta = " << etaMax << endl;
//
  cout << " Pi0 Isolation Cone = " << isocone << endl;
  cout << " Max dR between pi0 and Photon  = " << isodr << endl;
  cout << " 5x5 crystal cone  around pi0 axis in ECAL Barrel = " << deltaEB << endl;
  cout << " 5x5 crystal cone  around pi0 axis in ECAL Endcap = " << deltaEE << endl;

  theNumberOfTestedEvt = 0;
  theNumberOfSelected = 0;

}


PythiaFilterGammaJetIsoPi0::~PythiaFilterGammaJetIsoPi0(){}


// ------------ method called to produce the data  ------------
bool PythiaFilterGammaJetIsoPi0::filter(edm::Event& iEvent, const edm::EventSetup& iSetup){

  theNumberOfTestedEvt++;
  if(theNumberOfTestedEvt%1000 == 0) cout << "Number of tested events = " << theNumberOfTestedEvt <<  endl;
  
  bool accepted = false;
  Handle<edm::HepMCProduct> evt;
  iEvent.getByLabel(label_, evt);

  const HepMC::GenEvent * myGenEvent = evt->GetEvent();

  list<const HepMC::GenParticle *> pi0_seeds;

  int pi0_id = -1;
  int particle_id = 1;
  for ( HepMC::GenEvent::particle_const_iterator p = myGenEvent->particles_begin();  
                                                    p != myGenEvent->particles_end(); ++p ) {
   
    double Particle_pt = (*p)->momentum().perp();
    double Particle_eta = (*p)->momentum().eta();
              
    if ( (*p)->pdg_id()==111) {
      
      if(Particle_pt > PtMin && Particle_pt < PtMax &&  Particle_eta < etaMax  && Particle_eta > etaMin )
      {
         pi0_id = particle_id;
         pi0_seeds.push_back(*p);
         break;
      }
    }  
    particle_id++;
  }

  HepMC::GenEvent::particle_const_iterator ppp = myGenEvent->particles_begin();
  for(int i=0;i<7;++i) ppp++;
  HepMC::GenParticle* particle8 = (*ppp);

  int photon_id = 7;
  if(particle8->pdg_id() == 22) { 
    photon_id = 8;
  }

  if(pi0_seeds.size() == 1) {
    double eta_photon = myGenEvent->barcode_to_particle(photon_id)->momentum().eta();
    double phi_photon = myGenEvent->barcode_to_particle(photon_id)->momentum().eta();      
    double eta_pi0 = myGenEvent->barcode_to_particle(pi0_id)->momentum().eta();
    double phi_pi0 = myGenEvent->barcode_to_particle(pi0_id)->momentum().phi();

    double dr_pi0_photon = sqrt(deltaR2(eta_photon, phi_photon, eta_pi0, phi_pi0)); 
// check if pi0 comes from the jet and is far from the photon
// ----------------------------------------------------------    
    if(dr_pi0_photon > isodr) { 
      
      bool inEB(0);
      double tgx(0);
      double tgy(0);
      if( std::abs(eta_pi0) < ebEtaMax) inEB=1;
      else{
        tgx=myGenEvent->barcode_to_particle(pi0_id)->momentum().px()/myGenEvent->barcode_to_particle(pi0_id)->momentum().pz();
        tgy=myGenEvent->barcode_to_particle(pi0_id)->momentum().py()/myGenEvent->barcode_to_particle(pi0_id)->momentum().pz();
      }

      double etPi0=0;
      double etPi0Charged=0;
      double etCone=0;
      double etConeCharged=0;
      double ptMaxHadron=0;
        
      for ( HepMC::GenEvent::particle_const_iterator p = myGenEvent->particles_begin();
                                                 p != myGenEvent->particles_end(); ++p ) {
    
        if ( (*p)->status()!=1 ) continue; // use only stable particles
        int pid= (*p)->pdg_id();
        int apid= std::abs(pid);
        if (apid>11 &&  apid<21) continue; //get rid of muons and neutrinos
        double eta=(*p)->momentum().eta();
        double phi=(*p)->momentum().phi();
        if ( sqrt(deltaR2(eta_pi0, phi_pi0, eta, phi)) > isocone) continue;
        double pt=(*p)->momentum().perp();
        etCone+=pt; // add the pt if particle inside the cone
    
        ESHandle<ParticleDataTable> pdt;
        iSetup.getData( pdt );
    
        int charge3 = ((pdt->particle((*p)->pdg_id()))->ID().threeCharge());

        if(charge3) etConeCharged+=pt;

      //select particles matching a crystal array centered on pi0 direction
        if(inEB) {
      if(  std::abs(eta-eta_pi0)> deltaEB ||
           std::abs(deltaPhi(phi,phi_pi0)) > deltaEB) continue;
        }
        else if( fabs((*p)->momentum().px()/(*p)->momentum().pz() - tgx) > deltaEE || 
             fabs((*p)->momentum().py()/(*p)->momentum().pz() - tgy) > deltaEE) continue;

        etPi0+=pt;
    
        if(charge3) etPi0Charged+=pt;
    
        if(apid>100 && apid!=310 && pt>ptMaxHadron) ptMaxHadron=pt; // 310 -> K0s

      } // for ( HepMC::GenEvent::particle_const_iterator
      
    //isolation cuts

      double iso_cut1 = 5 + etPi0/20 - etPi0*etPi0/1e4;
      double iso_cut2 = 3 + etPi0/20 - etPi0*etPi0*etPi0/1e6;
      double iso_cut3 = 4.5 + etPi0/40;
      if (etPi0>165.)
      {
        iso_cut1 = 5.+165./20.-165.*165./1e4;
        iso_cut2 = 3.+165./20.-165.*165.*165./1e6;
        iso_cut3 = 4.5+165./40.;
      }
      double iso_cut4 = 0.02; // Fraction of charged energy in the cone 2% 


      double iso_val1 = etCone - etPi0; 
      double iso_val2 = iso_val1 - (etConeCharged - etPi0Charged);
      double iso_val3 = etConeCharged/etPi0;

      if( iso_val1 < iso_cut1) {
        if( iso_val2 < iso_cut2) {
           if(ptMaxHadron < iso_cut3) {
             if(iso_val3 < iso_cut4) {
               accepted=true;
         } 
           } // if(ptMaxHadron < iso_cut3)
    } // if( iso_val2 < iso_cut2) 
      } // if( iso_val1 < iso_cut1)         
    } // if(dr_pi0_jet < 0.1 && deta_pi0_photon > 1)
  } //if(pi0_seeds.size() == 1) {

  
  if (accepted) {
    theNumberOfSelected++;
    cout << "========>  Event: " << iEvent.id() 
         << " of Proccess ID " << myGenEvent->signal_process_id()
         <<  " preselected " << endl;
    cout << " Number of preselected events: " << theNumberOfSelected << endl;
    return true; 
  }
  else return false;

}