P4BaseEEtaPhiM.h

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef FOURMOM_P4BASEEETAPHIM_H
#define FOURMOM_P4BASEEETAPHIM_H
 
// STL includes
#include <cmath>
#include <ostream>
#include <sstream>
#include <iomanip>
 
// CLHEP includes
#include "CLHEP/Vector/LorentzVector.h"
#include "CLHEP/Units/SystemOfUnits.h"

 
 
class P4BaseEEtaPhiM
{
 public:

  virtual ~P4BaseEEtaPhiM();  

  // Const methods: 

 
  double px() const;
  double py() const;
  double pz() const;
  virtual double m() const = 0;
  double m2() const;
  double rapidity() const;
  double p() const;
  double p2() const;
  virtual double eta() const = 0;
  virtual double phi() const = 0;
  virtual double e() const = 0;
  double et() const;   
  double pt() const;
  double iPt() const;
  double sinPhi() const;
  double cosPhi() const;
  double tanTh() const;
  double cosTh() const;
  double sinTh() const;
  double cotTh() const;
  CLHEP::HepLorentzVector hlv() const;

  std::ostream& dump( std::ostream& out ) const;

  // Non-const methods: 

  // Protected data: 
 private: 
};

// Inline methods: 
 
inline P4BaseEEtaPhiM::~P4BaseEEtaPhiM()
{}
 
inline double P4BaseEEtaPhiM::px() const
{ 
  return this->pt()*cos(this->phi());
}
 
inline double P4BaseEEtaPhiM::py() const
{ 
  return this->pt()*sin(this->phi());
}
 
inline double P4BaseEEtaPhiM::pz() const
{ 
  return this->p()*this->cosTh();
}
 
inline double P4BaseEEtaPhiM::m2() const
{ 
  const double mass = this->m();
  return mass*mass;
}
 
inline double P4BaseEEtaPhiM::p() const 
{ 
  const double theM=this->m();
  const double theE=this->e();
  //  if (theM==0.) return theE ;
  //    else return sqrt(theE*theE-theM*theM); 
  //DR from Frank Paige
  // if negative energy point in the opposite direction
  // BUT eta and phi still the same !!!
  if (theM==0.) {
    return theE;
  } else {
    double eSign = (theE >= 0.) ? +1. : -1.;
    return eSign*std::sqrt(theE*theE-theM*theM); 
  }
 
}
 
inline double P4BaseEEtaPhiM::p2() const
{ 
  const double mass = this->m();
  const double ene  = this->e();
  
  return ene*ene - mass*mass;
}
 
inline double P4BaseEEtaPhiM::et() const
{
  return this->e()*this->sinTh();
}
 
inline double P4BaseEEtaPhiM::rapidity() const
  {
    const double theE=this->e();
    const double thePz=this->pz();
    return 0.5*std::log((theE+thePz)/(theE-thePz));
   }
 
inline double P4BaseEEtaPhiM::pt() const
{
  return this->p()*this->sinTh();
}
 
inline double P4BaseEEtaPhiM::iPt() const
{ 
  return 1./this->pt();
}
 
inline double P4BaseEEtaPhiM::cosPhi() const
{
 return std::cos(this->phi());
}
 
inline double P4BaseEEtaPhiM::sinPhi() const
{ 
  return std::sin(this->phi());
}
 
 
inline double P4BaseEEtaPhiM::tanTh() const
{ 
  double theEta=this->eta();
  if ( std::abs(theEta)>710) {
    theEta=theEta>0 ? 710 : -710;
    return 1./std::sinh(theEta);
  }
  return 1./this->cotTh();
}
 
inline double P4BaseEEtaPhiM::cosTh() const
{ 
  return std::tanh(this->eta());
}
 
inline double P4BaseEEtaPhiM::sinTh() const
{ 
  // avoid numeric overflow if very large eta
 
  double aEta=std::abs(this->eta());
  if ( aEta>710) {
    aEta=710;
  }
 
  return 1./std::cosh(aEta);
}
 
inline double P4BaseEEtaPhiM::cotTh() const
{ 
  return std::sinh(this->eta());
}
 
inline CLHEP::HepLorentzVector P4BaseEEtaPhiM::hlv() const
{
  //minimize the number of calculation and dereference
  const double theE = this->e();
  const double theCosTh = this->cosTh();  
  
  // DR from Frank Paige
  // negative energy point in opposite direction
  // BUT Eta and Phi still the same
  //  double theP=theE;
  
  const double theP = this->p();
  
  const double theSinTh = std::sqrt(1.-theCosTh*theCosTh);
  const double thePt = theP*theSinTh;
  const double thePx = thePt*this->cosPhi();
  const double thePy = thePt*this->sinPhi();
  const double thePz = theP*theCosTh;  
  
  return CLHEP::HepLorentzVector(thePx,thePy,thePz,theE);
}
 
inline std::ostream& P4BaseEEtaPhiM::dump( std::ostream& out ) const
{
  std::stringstream s;
  s << "[e,eta,phi,m] ="
    << std::right << std::scientific << std::setprecision(8) 
    << std::setw(16) << this->e()
    << std::setw(16) << this->eta()
    << std::setw(16) << this->phi()
    << std::setw(16) << this->m();
 
  out << s.str();
  return out;
 
}
 
 
#endif // FOURMOM_P4BASEEETAPHIM_H