FourVector.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * Forked from https://github.com/iLCSoft/MarlinKinfit                    *
 *                                                                        *
 * Further information about the fit engine and the user interface        *
 * provided in MarlinKinfit can be found at                               *
 * https://www.desy.de/~blist/kinfit/doc/html/                            *
 * and in the LCNotes LC-TOOL-2009-001 and LC-TOOL-2009-004 available     *
 * from http://www-flc.desy.de/lcnotes/                                   *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#ifndef __FOURVECTOR_H
#define __FOURVECTOR_H
 
#include "analysis/OrcaKinFit/ThreeVector.h"
 
#include <iostream>
#include <cmath>
#include <cassert>
 
namespace Belle2 {
  namespace OrcaKinFit {
 
//  Class FourVector:
 
    class FourVector {
    public:
      inline FourVector();
      inline FourVector(double E_, double px_, double py_, double pz_);
      inline FourVector(double E_, const ThreeVector& p_);
      inline FourVector(const ThreeVector& p_, double m_);
      // automatically generated copy constructor and assignment is fine
 
      inline double getE()     const;
      inline double getPx()    const;
      inline double getPy()    const;
      inline double getPz()    const;
      inline double getM2()    const;
      inline double getM()     const;
      inline double getMass()     const;
 
      inline double getP2()    const;
      inline double getP()     const;
      inline double getPt2()   const;
      inline double getPt()    const;
 
      inline double getPhi()   const;
      inline double getTheta() const;
      inline double getEta() const;
 
      inline double getComponent(int i) const;
 
      inline ThreeVector getBeta() const { assert(E > 0); return (1. / E) * p;};
      inline double getGamma() const { assert(getM() > 0); return getE() / getM();};
      inline ThreeVector getBetaGamma() const { assert(getM() > 0); return (1. / getM() > 0) * p;};
 
      inline const ThreeVector& getThreeVector() const { return p;}
 
      FourVector& boost(const FourVector& P);
      void decayto(FourVector& d1, FourVector& d2) const;
 
      inline void setValues(double E_, double px_, double py_, double pz_);
 
      inline FourVector& operator+= (const FourVector& rhs);
      inline FourVector& operator-= (const FourVector& rhs);
 
      inline FourVector& operator*= (double rhs);
 
    private:
      double E;         
      ThreeVector p;    
    };
 
    FourVector::FourVector()
      : E(0), p()
    {}
 
    FourVector::FourVector(double E_, double px_, double py_, double pz_)
      : E(E_), p(px_, py_, pz_)
    {}
 
    FourVector::FourVector(double E_, const ThreeVector& p_)
      : E(E_), p(p_)
    {}
 
    FourVector::FourVector(const ThreeVector& p_, double m)
      : E(std::sqrt(p_.getP2() + m * m)), p(p_)
    {}
 
    double FourVector::getE()  const { return E; }
    double FourVector::getPx() const { return p.getPx(); }
    double FourVector::getPy() const { return p.getPy(); }
    double FourVector::getPz() const { return p.getPz(); }
 
    double FourVector::getPt2() const { return p.getPt2(); }
    double FourVector::getPt()  const { return p.getPt(); }
 
    double FourVector::getP2() const { return p.getP2(); }
    double FourVector::getP()  const { return p.getP(); }
 
    double FourVector::getM2()   const { return std::abs(getE() * getE() - getP2()); }
    double FourVector::getM()    const { return std::sqrt(getM2()); }
    double FourVector::getMass() const { return std::sqrt(getM2()); }
 
    double FourVector::getPhi()   const { return p.getPhi(); }
    double FourVector::getTheta() const { return p.getTheta(); }
 
    double FourVector::getEta() const { return p.getEta(); }
 
    double FourVector::getComponent(int i) const
    {
      switch (i) {
        case 1: return getPx();
        case 2: return getPy();
        case 3: return getPz();
      }
      return getE();
    }
 
    void FourVector::setValues(double E_, double px_, double py_, double pz_)
    {
      E = E_;
      p.setValues(px_, py_, pz_);
    }
 
    FourVector& FourVector::operator+= (const FourVector& rhs)
    {
      p += rhs.p;
      E += rhs.E;
      return *this;
    }
 
    FourVector& FourVector::operator-= (const FourVector& rhs)
    {
      p -= rhs.p;
      E -= rhs.E;
      return *this;
    }
 
    FourVector& FourVector::operator*= (double rhs)
    {
      p *= rhs;
      E *= rhs;
      return *this;
    }
 
    inline FourVector operator+ (const FourVector& lhs, const FourVector& rhs)
    {
      return FourVector(lhs.getE() + rhs.getE(), lhs.getPx() + rhs.getPx(), lhs.getPy() + rhs.getPy(), lhs.getPz() + rhs.getPz());
    }
 
    inline FourVector operator- (const FourVector& lhs, const FourVector& rhs)
    {
      return FourVector(lhs.getE() - rhs.getE(), lhs.getPx() - rhs.getPx(), lhs.getPy() - rhs.getPy(), lhs.getPz() - rhs.getPz());
    }
 
    inline FourVector operator- (const FourVector& rhs)
    {
      return FourVector(-rhs.getE(), -rhs.getPx(), -rhs.getPy(), -rhs.getPz());
    }
 
    inline FourVector operator* (double lhs, const FourVector& rhs)
    {
      return FourVector(lhs * rhs.getE(), lhs * rhs.getPx(), lhs * rhs.getPy(), lhs * rhs.getPz());
    }
 
    inline double operator* (const FourVector& lhs, const FourVector& rhs)
    {
      return lhs.getE() * rhs.getE() - lhs.getPx() * rhs.getPx() - lhs.getPy() * rhs.getPy() - lhs.getPz() * rhs.getPz();
    }
 
 
    inline std::ostream& operator<< (std::ostream& os,
                                     const FourVector& rhs
                                    )
    {
      os << "(" << rhs.getE() << ", " << rhs.getPx() << ", " << rhs.getPy() << ", " << rhs.getPz() << ")";
      return os;
    }
 
  }// end OrcaKinFit namespace
} // end Belle2 namespace
 
#endif // __FOURVECTOR_H