TauPi0Candidate.icc

Go to the documentation of this file.

// dear emacs, this is -*- C++ -*-
 
/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
 
//using namespace CLHEP;
 
#include "TruthUtils/ParticleConstants.h"
 
namespace Analysis{
  
    //-------------------------------------------------------------------------
    // clusters
    //-------------------------------------------------------------------------
 
    inline const TauPi0Cluster* TauPi0Candidate::pi0Cluster(unsigned int i) const
    {
        return m_pi0ClusterVector[i];
    }
 
    inline const std::vector<TauPi0Cluster*>& TauPi0Candidate::pi0ClusterVec() const
    {
      return m_pi0ClusterVector ;
    }
  
    inline std::vector<TauPi0Cluster*>& TauPi0Candidate::pi0ClusterVec()
    {
      return m_pi0ClusterVector;
    }
 
    inline unsigned int TauPi0Candidate::nPi0Cluster() const
    {
        return m_pi0ClusterVector.size();
    }
 
    inline CLHEP::HepLorentzVector TauPi0Candidate::hlv() const
    {
      CLHEP::HepLorentzVector cand4Mom(0., 0., 0., 0.);
      double mPi0 = ParticleConstants::piZeroMassInMeV;
      if(this->nPi0Cluster() == 1){
 
        // Cluster E has been measured in Calo. Cluster Pt has been calculated using a 0 mass hypthesis.
        // Therefore recalculate Cluster Pt using pi0 mass hypothesis
        double clusterE = this->pi0Cluster( 0 )->cluster()->e();
        double clusterEta = this->pi0Cluster( 0 )->cluster()->eta();
        // Make sure clusterE>=mPi0, since sqrt(clusterE*clusterE-mPi0*mPi0) is used
        if(clusterE<mPi0) clusterE = mPi0;
        double clusterPt = std::sqrt(clusterE*clusterE-mPi0*mPi0)/std::cosh(clusterEta);
 
        // Set hlv. Steps are copied from /atlas/Trigger/TrigAlgorithms/TrigDiMuon/src/TrigDiMuonFast.cxx
        double clusterPhi = this->pi0Cluster( 0 )->cluster()->phi();
 
        double cot=1/std::tan(2*std::atan(std::exp(-clusterEta)));
        double px=std::cos(clusterPhi)*clusterPt;
        double py=std::sin(clusterPhi)*clusterPt;
        double pz=cot*clusterPt;
 
        cand4Mom = CLHEP::HepLorentzVector(px,py,pz,clusterE);
      }
      // TODO: Reconsider how to define the hlv for nPi0Cluster!=1. 
      else if(this->nPi0Cluster() != 0){
        for(unsigned iCluster=0; iCluster<this->nPi0Cluster();++iCluster){
          cand4Mom+=this->pi0Cluster( iCluster )->cluster()->hlv();
        }
        // Recalculate Candidate Pt using pi0 mass hypothesis
        double candidatePt = std::sqrt(cand4Mom.e()*cand4Mom.e()-mPi0*mPi0)/std::cosh(cand4Mom.eta());
 
        // Set hlv. Steps are copied from /atlas/Trigger/TrigAlgorithms/TrigDiMuon/src/TrigDiMuonFast.cxx
        double cot=1/std::tan(2*std::atan(std::exp(-cand4Mom.eta())));
        double px=std::cos(cand4Mom.phi())*candidatePt;
        double py=std::sin(cand4Mom.phi())*candidatePt;
        double pz=cot*candidatePt;
        
        cand4Mom = CLHEP::HepLorentzVector(px,py,pz,cand4Mom.e());
      }
      return cand4Mom;
    }
 
    inline void TauPi0Candidate ::addPi0Cluster( TauPi0Cluster *pi0Cluster )
    {
      m_pi0ClusterVector.push_back( pi0Cluster );
    }
} //end of namespace analysis