CbmAnaConversionKinematicParams.h

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/* Copyright (C) 2015-2016 Fakultaet fuer Mathematik und Naturwissenschaften, Bergische Universitaet Wuppertal, Wuppertal
   SPDX-License-Identifier: GPL-3.0-only
   Authors: Sascha Reinecke [committer]  */
 
#ifndef CBM_ANA_CONVERSION_KINEMATIC_PARAMS
#define CBM_ANA_CONVERSION_KINEMATIC_PARAMS
 
#include "CbmMCTrack.h"
 
#include "TLorentzVector.h"
#include "TMath.h"
 
#define M2E 2.6112004954086e-7
 
class CbmAnaConversionKinematicParams {
public:
  Double_t fMomentumMag = 0;  // Absolute value of momentum
  Double_t fPt          = 0;  // Transverse momentum
  Double_t fRapidity    = 0;  // Rapidity
  Double_t fMinv        = 0;  // Invariant mass
  Double_t fAngle       = 0;  // Opening angle
  Double_t fRap2        = 0;
  Double_t fPseudoRap2  = 0;
 
  /*
    * Calculate kinematic parameters for MC tracks.
    */
  static CbmAnaConversionKinematicParams KinematicParams_4particles_MC(const CbmMCTrack* mctrack1,
                                                                       const CbmMCTrack* mctrack2,
                                                                       const CbmMCTrack* mctrack3,
                                                                       const CbmMCTrack* mctrack4)
  {
    CbmAnaConversionKinematicParams params;
 
    TLorentzVector lorVec1;
    mctrack1->Get4Momentum(lorVec1);
    TVector3 part1   = lorVec1.Vect();
    Double_t energy1 = lorVec1.Energy();
 
    TLorentzVector lorVec2;
    mctrack2->Get4Momentum(lorVec2);
    TVector3 part2   = lorVec2.Vect();
    Double_t energy2 = lorVec2.Energy();
 
    TLorentzVector lorVec3;
    mctrack3->Get4Momentum(lorVec3);
    TVector3 part3   = lorVec3.Vect();
    Double_t energy3 = lorVec3.Energy();
 
    TLorentzVector lorVec4;
    mctrack4->Get4Momentum(lorVec4);
    TVector3 part4   = lorVec4.Vect();
    Double_t energy4 = lorVec4.Energy();
 
    TLorentzVector sum;
    sum = lorVec1 + lorVec2 + lorVec3 + lorVec4;
 
    TVector3 momPair    = part1 + part2 + part3 + part4;
    Double_t energyPair = energy1 + energy2 + energy3 + energy4;
    Double_t pzPair     = momPair.Pz();
    Double_t yPair      = 0.5 * TMath::Log((energyPair + pzPair) / (energyPair - pzPair));
 
    Double_t invmass = sum.Mag();
 
    Double_t perp = sum.Perp();
    //Double_t pt = TMath::Sqrt(sum.X() * sum.X() + sum.Y() * sum.Y() );
 
 
    params.fMomentumMag = momPair.Mag();
    params.fPt          = perp;
    params.fRapidity    = yPair;
    params.fMinv        = invmass;
    params.fRap2        = sum.Rapidity();
    params.fPseudoRap2  = sum.PseudoRapidity();
    return params;
  }
 
  /*
    * Calculate kinematic parameters for reconstructed momenta
    */
  static CbmAnaConversionKinematicParams KinematicParams_4particles_Reco(const TVector3 part1, const TVector3 part2,
                                                                         const TVector3 part3, const TVector3 part4)
  {
    CbmAnaConversionKinematicParams params;
 
    Double_t energy1 = TMath::Sqrt(part1.Mag2() + M2E);
    TLorentzVector lorVec1(part1, energy1);
 
    Double_t energy2 = TMath::Sqrt(part2.Mag2() + M2E);
    TLorentzVector lorVec2(part2, energy2);
 
    Double_t energy3 = TMath::Sqrt(part3.Mag2() + M2E);
    TLorentzVector lorVec3(part3, energy3);
 
    Double_t energy4 = TMath::Sqrt(part4.Mag2() + M2E);
    TLorentzVector lorVec4(part4, energy4);
 
    TLorentzVector sum;
    sum = lorVec1 + lorVec2 + lorVec3 + lorVec4;
 
    TVector3 momPair    = part1 + part2 + part3 + part4;
    Double_t energyPair = energy1 + energy2 + energy3 + energy4;
    Double_t pzPair     = momPair.Pz();
    Double_t yPair      = 0.5 * TMath::Log((energyPair + pzPair) / (energyPair - pzPair));
 
    Double_t invmass = sum.Mag();
 
    Double_t perp = sum.Perp();
    //Double_t pt = TMath::Sqrt(sum.X() * sum.X() + sum.Y() * sum.Y() );
 
 
    params.fMomentumMag = momPair.Mag();
    params.fPt          = perp;
    params.fRapidity    = yPair;
    params.fMinv        = invmass;
    params.fRap2        = sum.Rapidity();
    params.fPseudoRap2  = sum.PseudoRapidity();
    return params;
  }
 
 
  static CbmAnaConversionKinematicParams KinematicParams_2particles_Reco(const TVector3 electron1,
                                                                         const TVector3 electron2)
  {
    CbmAnaConversionKinematicParams params;
 
    Double_t energyP = TMath::Sqrt(electron1.Mag2() + M2E);
    TLorentzVector lorVecP(electron1, energyP);
 
    Double_t energyM = TMath::Sqrt(electron2.Mag2() + M2E);
    TLorentzVector lorVecM(electron2, energyM);
 
    TVector3 momPair    = electron1 + electron2;
    Double_t energyPair = energyP + energyM;
    Double_t ptPair     = momPair.Perp();
    Double_t pzPair     = momPair.Pz();
    Double_t yPair      = 0.5 * TMath::Log((energyPair + pzPair) / (energyPair - pzPair));
    Double_t anglePair  = lorVecM.Angle(lorVecP.Vect());
    Double_t theta      = 180. * anglePair / TMath::Pi();
    Double_t minv       = 2. * TMath::Sin(anglePair / 2.) * TMath::Sqrt(electron1.Mag() * electron2.Mag());
 
    params.fMomentumMag = momPair.Mag();
    params.fPt          = ptPair;
    params.fRapidity    = yPair;
    params.fMinv        = minv;
    params.fAngle       = theta;
    return params;
  }
};
 
#endif