TracksInCone.h

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
// ======================================================================
// TracksInCone
// James.Catmore@cern.ch
// Given an xAOD::IParticle and an IDTrackParticle container, checks 
// which tracks are in a cone of a given size around the IParticle. Sets
// a mask accordingly. Intended for thinning use.
// ======================================================================
#pragma once
 
#include "xAODBase/IParticle.h"
#include "xAODTracking/TrackParticleContainer.h"
#include "xAODTau/TauTrackContainer.h"
 
namespace DerivationFramework {
    struct TracksInCone{
        
        void select(const xAOD::IParticle* particle, float coneSize, const xAOD::TrackParticleContainer* tracks, std::vector<bool> &mask) {
            float particleEta = particle->eta();
            float particlePhi = particle->phi();
            unsigned int i(0);
            for (xAOD::TrackParticleContainer::const_iterator trIt = tracks->begin(); trIt!=tracks->end(); ++trIt, ++i) {
                float deltaEta = (*trIt)->eta() - particleEta;
                float deltaPhi = fabs((*trIt)->phi() - particlePhi);
                if (deltaPhi > TMath::Pi()) deltaPhi = 2.0*TMath::Pi() - deltaPhi;
                float deltaR = sqrt(deltaEta*deltaEta + deltaPhi*deltaPhi);
                if (deltaR < coneSize) mask[i] = true;
            }
            return;
        }
          
      // Extend the functionality to tau tracks for consistency (TauTrackParticleThinning),
      // although it's not recommended to select tau tracks based on dR;
      // the selection should only rely on the tau track classification
      void select(const xAOD::IParticle* particle, float coneSize, const xAOD::TauTrackContainer* tracks, std::vector<bool> &mask) {
        float particleEta = particle->eta();
        float particlePhi = particle->phi();
        unsigned int i(0);
        for (xAOD::TauTrackContainer::const_iterator trIt = tracks->begin(); trIt!=tracks->end(); ++trIt, ++i) {
          float deltaEta = (*trIt)->eta() - particleEta;
          float deltaPhi = fabs((*trIt)->phi() - particlePhi);
          if (deltaPhi > TMath::Pi()) deltaPhi = 2.0*TMath::Pi() - deltaPhi;
          float deltaR = sqrt(deltaEta*deltaEta + deltaPhi*deltaPhi);
          if (deltaR < coneSize) mask[i] = true;
        }
        return;
      }
    };
}