GenParticleJet.h

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/

// GenParticleJet.h
//   Header file for GenParticleJet helper class
// (c) ATLAS Detector software
 
#ifndef TRK_TRKVALEVENT_GENPARTICLEJET_H
#define TRK_TRKVALEVENT_GENPARTICLEJET_H
 
#include <vector>
#include <utility>
#include "CLHEP/Geometry/Vector3D.h"
#include "AtlasHepMC/GenParticle.h"
 
namespace Trk {

 
class GenParticleJet
{
  
 public:
  GenParticleJet(): m_particles(), m_indices(), m_energy(0.), m_momentum(0.0, 0.0, 0.0), m_totalPt2(0.), m_totalMom2(0.), m_pDotJetAxis(0.), m_magP(0.)
    {
        
    }; // constructor
 
  ~GenParticleJet(){}; // destructor
  
  void setEnergy(double energy){m_energy = energy;}
 
  double getEnergy() const {return m_energy;}
  
  HepMC::ConstGenParticlePtr getParticle (unsigned int i) const
    {
      return m_particles.at(i);
    }
  std::pair<HepMC::ConstGenParticlePtr,int> getIndexedParticle(unsigned int i)
    {
      return std::make_pair(m_particles.at(i),m_indices.at(i));
    }
  
  const std::vector<HepMC::ConstGenParticlePtr >& getParticles() const {return m_particles;}
 
  const std::vector<int>& getIndicesInEvent() const {return m_indices;}
 
  int getNumParticles() const {return m_particles.size();}
  
  void addParticle(HepMC::ConstGenParticlePtr part,
                   int indexInEvent = -1 ){
    m_particles.push_back(part);
    m_indices.push_back(indexInEvent);
    m_energy = m_energy + part->momentum().e();
    HepGeom::Vector3D<double> moment(part->momentum().px(), part->momentum().py(), part->momentum().pz());
    m_momentum = m_momentum + moment;
 
    m_totalMom2 = m_totalMom2 + pow((moment.mag()), 2);
    m_magP = m_magP + moment.mag();
    HepGeom::Vector3D<double> partMom(part->momentum().px(), part->momentum().py(), part->momentum().pz());
    double longMoment = partMom.dot((m_momentum)/(m_momentum.mag()));
    m_pDotJetAxis = m_pDotJetAxis + longMoment;
    m_totalPt2 = m_totalPt2 + pow(partMom.mag(), 2) - pow(longMoment, 2);
  }
 
  HepGeom::Vector3D<double> getMomentum() const {return m_momentum;}
 
  double getThrust() const {return m_pDotJetAxis/m_magP;}
  double getSphericity() const {return m_totalPt2/m_totalMom2;}
  
 
 private:
  std::vector<HepMC::ConstGenParticlePtr > m_particles;
  std::vector< int > m_indices;
  double m_energy;
  HepGeom::Vector3D<double>  m_momentum;
  double m_totalPt2;
  double m_totalMom2;
  double m_pDotJetAxis;
  double m_magP;
};
 
} // end of namespace
 
#endif // TRK_TRKVALEVENT_GENPARTICLEJET_H