PhotonTkIsolation.cc

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//*****************************************************************************
// File:      PhotonTkIsolation.cc
// ----------------------------------------------------------------------------
// OrigAuth:  Matthias Mozer
// Institute: IIHE-VUB
//=============================================================================
//*****************************************************************************
//C++ includes
#include <vector>
#include <functional>
 
//ROOT includes
#include <Math/VectorUtil.h>
 
//CMSSW includes
#include "RecoEgamma/EgammaIsolationAlgos/interface/PhotonTkIsolation.h"
#include "DataFormats/TrackReco/interface/TrackFwd.h"
#include "TrackingTools/PatternTools/interface/Trajectory.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateTransform.h"
#include "DataFormats/GeometryVector/interface/GlobalPoint.h"
#include "DataFormats/GeometryVector/interface/GlobalVector.h"
#include "DataFormats/RecoCandidate/interface/RecoCandidate.h"
#include "DataFormats/EgammaReco/interface/SuperCluster.h"
#include "DataFormats/EgammaReco/interface/SuperClusterFwd.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrack.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/Candidate/interface/Particle.h"
 
PhotonTkIsolation::PhotonTkIsolation(float extRadius,
                                     float intRadiusBarrel,
                                     float intRadiusEndcap,
                                     float stripBarrel,
                                     float stripEndcap,
                                     float etLow,
                                     float lip,
                                     float drb,
                                     const reco::TrackCollection* trackCollection,
                                     reco::TrackBase::Point beamPoint,
                                     const std::string& dzOptionString)
    : extRadius2_(extRadius * extRadius),
      intRadiusBarrel2_(intRadiusBarrel * intRadiusBarrel),
      intRadiusEndcap2_(intRadiusEndcap * intRadiusEndcap),
      stripBarrel_(stripBarrel),
      stripEndcap_(stripEndcap),
      etLow_(etLow),
      lip_(lip),
      drb_(drb),
      trackCollection_(trackCollection),
      beamPoint_(beamPoint) {
  setDzOption(dzOptionString);
}
 
void PhotonTkIsolation::setDzOption(const std::string& s) {
  if (!s.compare("dz"))
    dzOption_ = egammaisolation::EgammaTrackSelector::dz;
  else if (!s.compare("vz"))
    dzOption_ = egammaisolation::EgammaTrackSelector::vz;
  else if (!s.compare("bs"))
    dzOption_ = egammaisolation::EgammaTrackSelector::bs;
  else if (!s.compare("vtx"))
    dzOption_ = egammaisolation::EgammaTrackSelector::vtx;
  else
    dzOption_ = egammaisolation::EgammaTrackSelector::dz;
}
 
PhotonTkIsolation::~PhotonTkIsolation() {}
 
// unified acces to isolations
std::pair<int, float> PhotonTkIsolation::getIso(const reco::Candidate* photon) const {
  int counter = 0;
  float ptSum = 0.;
 
  //Take the photon position
  float photonEta = photon->eta();
 
  //loop over tracks
  for (reco::TrackCollection::const_iterator trItr = trackCollection_->begin(); trItr != trackCollection_->end();
       ++trItr) {
    //check z-distance of vertex
    float dzCut = 0;
    switch (dzOption_) {
      case egammaisolation::EgammaTrackSelector::dz:
        dzCut = fabs((*trItr).dz() - photon->vertex().z());
        break;
      case egammaisolation::EgammaTrackSelector::vz:
        dzCut = fabs((*trItr).vz() - photon->vertex().z());
        break;
      case egammaisolation::EgammaTrackSelector::bs:
        dzCut = fabs((*trItr).dz(beamPoint_) - photon->vertex().z());
        break;
      case egammaisolation::EgammaTrackSelector::vtx:
        dzCut = fabs((*trItr).dz(photon->vertex()));
        break;
      default:
        dzCut = fabs((*trItr).vz() - photon->vertex().z());
        break;
    }
    if (dzCut > lip_)
      continue;
 
    float this_pt = (*trItr).pt();
    if (this_pt < etLow_)
      continue;
    if (fabs((*trItr).dxy(beamPoint_)) > drb_)
      continue;  // only consider tracks from the main vertex
    float dr2 = reco::deltaR2(*trItr, *photon);
    float deta = (*trItr).eta() - photonEta;
    if (fabs(photonEta) < 1.479) {
      if (dr2 < extRadius2_ && dr2 >= intRadiusBarrel2_ && fabs(deta) >= stripBarrel_) {
        ++counter;
        ptSum += this_pt;
      }
    } else {
      if (dr2 < extRadius2_ && dr2 >= intRadiusEndcap2_ && fabs(deta) >= stripEndcap_) {
        ++counter;
        ptSum += this_pt;
      }
    }
 
  }  //end loop over tracks
 
  std::pair<int, float> retval;
  retval.first = counter;
  retval.second = ptSum;
  return retval;
}