TruthParticleTraits.h

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/* emacs: this is -*- c++ -*- */
 
 
#ifndef  TRUTHPARTICLETRAITS_H
#define  TRUTHPARTICLETRAITS_H
 
#include "xAODTruth/TruthParticle.h"
 
#include "TrackTraits.h"
 
#include <cmath>

 
template<>
struct TrackTraits<xAOD::TruthParticle> : public TrackTraitsBase<xAOD::TruthParticle> {

 
  using Accessor = SG::ConstAccessor<float>;
    
  static float theta(const xAOD::TruthParticle& t) { return 2*std::atan(std::exp(-t.eta())); }
  static float     E(const xAOD::TruthParticle& t) { return t.e(); }
  static float    ET(const xAOD::TruthParticle& t) { return t.e()*std::sin(theta(t)); }
  static float     p(const xAOD::TruthParticle& t) { return t.charge()*std::sqrt( t.px()*t.px() + t.py()*t.py() + t.pz()*t.pz() ); }
 
  static float     m(const xAOD::TruthParticle& t) { return t.m(); }

  
  static float z0(const xAOD::TruthParticle& t) {
    static const Accessor acc("z0");
    return acc(t);
  }
  
  static float d0(const xAOD::TruthParticle& t) {
    static const Accessor acc("d0");
    return acc(t);
  }
 
  static float phi(const xAOD::TruthParticle& t) {
    static const Accessor acc("phi");
    return acc(t);
  }
 
  static float  qOverP(const xAOD::TruthParticle& t) {
    float p_ = p(t);
    if ( p_==0 ) throw std::runtime_error( "divide by 0 - track p() is 0" );
    return 1/p_;
  }
  
};
 
 
#endif  // TRUTHPARTICLETRAITS_H