/data/refman/pasoursint/CMSSW_6_1_2_SLHC4_patch1/src/JetMETCorrections/JetVertexAssociation/src/JetVertexMain.cc

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#include "JetMETCorrections/JetVertexAssociation/interface/JetVertexMain.h"
#include "DataFormats/JetReco/interface/CaloJet.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/TrackReco/interface/TrackFwd.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include <cmath>
#include <string>
using namespace reco;
using namespace edm;

JetVertexMain::JetVertexMain(const ParameterSet & parameters) {

  cutSigmaZ = parameters.getParameter<double>("JV_sigmaZ");
  cutDeltaZ = parameters.getParameter<double>("JV_deltaZ");
  threshold = parameters.getParameter<double>("JV_alpha_threshold");
  cone_size = parameters.getParameter<double>("JV_cone_size");
  Algo =  parameters.getParameter<int>("JV_type_Algo");
  cutType = parameters.getParameter<std::string>("JV_cutType");

}


std::pair<double,bool> JetVertexMain::Main(const reco::CaloJet& jet, edm::Handle<TrackCollection> tracks,
                                           double signal_vert_Z,  double signal_vert_z_error){

  std::pair<double, bool> parameter; 
 
  double jet_et = jet.et();
  double jet_phi = jet.phi();
  double jet_eta = jet.eta();

  //  cout<<"JET: "<<jet_et<<endl;
  double Pt_jets_X = 0. ;
  double Pt_jets_Y = 0. ;
  double Pt_jets_X_tot = 0. ;
  double Pt_jets_Y_tot = 0. ;

  TrackCollection::const_iterator track = tracks->begin ();

  if (tracks->size() > 0 )   { 
   for (; track != tracks->end (); track++) {
     double Vertex_Z = track->vz();
     double Vertex_Z_Error = track->dzError();
     double track_eta = track->eta();
     double track_phi = track->phi();

     if (DeltaR(track_eta,jet_eta, track_phi, jet_phi) < cone_size) {

                  double DeltaZ = Vertex_Z-signal_vert_Z;
                  double DeltaZ_Error = sqrt((Vertex_Z_Error*Vertex_Z_Error)+(signal_vert_z_error*signal_vert_z_error));
                  Pt_jets_X_tot += track->px();
                  Pt_jets_Y_tot += track->py();  
                  if (cutType == "sig") discriminator = (fabs(DeltaZ)/DeltaZ_Error) <= cutSigmaZ;
                  else discriminator = fabs(DeltaZ) < cutDeltaZ;
        
                  if (discriminator){
                    
                      Pt_jets_X += track->px();
                      Pt_jets_Y += track->py();
                       
                  }
 
   }
 } 
}
  double Var = -1;
  
  if (Algo == 1) Var =  Track_Pt(Pt_jets_X, Pt_jets_Y)/jet_et;
  else if (Algo == 2) {
      if (Track_Pt(Pt_jets_X_tot, Pt_jets_Y_tot)!=0)  Var =  Track_Pt(Pt_jets_X, Pt_jets_Y)/Track_Pt(Pt_jets_X_tot, Pt_jets_Y_tot);
      else  std::cout << "[Jets] JetVertexAssociation: Warning! problems for  Algo = 2: possible division by zero .." << std::endl;
  }
  else {
    
      Var =  Track_Pt(Pt_jets_X, Pt_jets_Y)/jet_et;
      std::cout << "[Jets] JetVertexAssociation: Warning! Algo = " << Algo << " not found; using Algo = 1" << std::endl;
  }

  //  cout<<"Var = "<<Var<<endl;

  if (Var >= threshold) parameter = std::pair<double, bool>(Var, true);
  else  parameter = std::pair<double, bool>(Var, false);

  return parameter;

}

double JetVertexMain::DeltaR(double eta1, double eta2, double phi1, double phi2){

  double dphi = fabs(phi1-phi2);
  if(dphi > M_PI) dphi = 2*M_PI - dphi;
  double deta = fabs(eta1-eta2);
  return sqrt(dphi*dphi + deta*deta);

}

double JetVertexMain::Track_Pt(double px, double py){

  return sqrt(px*px+py*py);

}