G4Parton.cc

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//
//
//
// ------------------------------------------------------------
//      GEANT 4 class implementation file
//
//      ---------------- G4Parton ----------------
//             by Gunter Folger, June 1998.
//       class for Parton (inside a string) used by Parton String Models
// ------------------------------------------------------------

#include "G4Parton.hh"
#include "G4HadronicException.hh"

G4Parton::G4Parton(G4int PDGcode)
{
        PDGencoding=PDGcode;
        theX = 0;
        theDefinition=G4ParticleTable::GetParticleTable()->FindParticle(PDGencoding);
        if (theDefinition == NULL)
        {
          G4cout << "Encoding = "<<PDGencoding<<G4endl;
          G4String text = "G4Parton::GetDefinition(): Encoding not in particle table";
          throw G4HadronicException(__FILE__, __LINE__, text);
        }
        //
        // colour by random in (1,2,3)=(R,G,B) for quarks and 
        //                  in (-1,-2,-3)=(Rbar,Gbar,Bbar) for anti-quarks:
  //
        if (theDefinition->GetParticleType() == "quarks") {
                theColour = ((G4int)(3.*G4UniformRand())+1)*(std::abs(PDGencoding)/PDGencoding) ;
        }
        //
        // colour by random in (-1,-2,-3)=(Rbar,Gbar,Bbar)=(GB,RB,RG) for di-quarks and
        //                  in (1,2,3)=(R,G,B)=(GB,RB,RG) for anti-di-quarks:
  //
        else if (theDefinition->GetParticleType() == "diquarks") {
                theColour = -((G4int)(3.*G4UniformRand())+1)*(std::abs(PDGencoding)/PDGencoding);
        }
        //
        // colour by random in (-11,-12,...,-33)=(RRbar,RGbar,RBbar,...,BBbar) for gluons:
  //
        else if (theDefinition->GetParticleType() == "gluons") {
                theColour = -(((G4int)(3.*G4UniformRand())+1)*10 + ((G4int)(3.*G4UniformRand())+1));
        }
        else {
          G4cout << "Encoding = "<<PDGencoding<<G4endl;
          G4String text = "G4Parton::GetDefinition(): Particle is not a parton";
          throw G4HadronicException(__FILE__, __LINE__, text);
        }
        //  
        // isospin-z from PDG-encoded isospin-z for 
        // quarks, anti-quarks, di-quarks, and anti-di-quarks:
  //
        if ((theDefinition->GetParticleType() == "quarks") || (theDefinition->GetParticleType() == "diquarks")){
                theIsoSpinZ = theDefinition->GetPDGIsospin3();
        }
        //
  // isospin-z choosen at random from PDG-encoded isospin for gluons (should be zero):
        //
        else {
                G4int thisPDGiIsospin=theDefinition->GetPDGiIsospin();
                if (thisPDGiIsospin == 0) {
                        theIsoSpinZ = 0;
                }
                else {
                        theIsoSpinZ = ((G4int)((thisPDGiIsospin+1)*G4UniformRand()))-thisPDGiIsospin*0.5;
                }
        }
        //
        // spin-z choosen at random from PDG-encoded spin:
        //
        G4int thisPDGiSpin=theDefinition->GetPDGiSpin();
        if (thisPDGiSpin == 0) {
                theSpinZ = 0;
        }
        else {
                G4int rand=((G4int)((thisPDGiSpin+1)*G4UniformRand()));
                theSpinZ = rand-thisPDGiSpin*0.5;;
        }
}

G4Parton::G4Parton(const G4Parton &right)
{
        PDGencoding = right.PDGencoding;
        theMomentum = right.theMomentum;
        thePosition = right.thePosition;
        theX = right.theX;
        theDefinition = right.theDefinition;
        theColour = right.theColour;
        theIsoSpinZ = right.theIsoSpinZ;
        theSpinZ = right.theSpinZ;
}

G4Parton & G4Parton::operator=(const G4Parton &right)
{
   if (this != &right)
   {
      PDGencoding=right.GetPDGcode();
      theMomentum=right.Get4Momentum();
      thePosition=right.GetPosition();
      theX = right.theX;
      theDefinition = right.theDefinition;
      theColour = right.theColour;
      theIsoSpinZ = right.theIsoSpinZ;
      theSpinZ = right.theSpinZ;
   }

        return *this;
}

G4Parton::~G4Parton()
{
//  cout << "G4Parton::~G4Parton(): this = "<<this <<endl;
//  cout << "break here"<<this <<endl;
}

void G4Parton::DefineMomentumInZ(G4double aLightConeMomentum, G4bool aDirection)
{
        G4double Mass = GetMass();
        G4LorentzVector a4Momentum = Get4Momentum();
        aLightConeMomentum*=theX;
        G4double TransverseMass2 = sqr(a4Momentum.px()) + sqr(a4Momentum.py()) + sqr(Mass);
        a4Momentum.setPz(0.5*(aLightConeMomentum - TransverseMass2/aLightConeMomentum)*(aDirection? 1: -1)); 
        a4Momentum.setE( 0.5*(aLightConeMomentum + TransverseMass2/aLightConeMomentum));
        Set4Momentum(a4Momentum);
}  

void G4Parton::DefineMomentumInZ(G4double aLightConeMomentum,G4double aLightConeE, G4bool aDirection)
{
        G4double Mass = GetMass();
        G4LorentzVector a4Momentum = Get4Momentum();
        aLightConeMomentum*=theX;
        aLightConeE*=theX;
        G4double TransverseMass2 = sqr(a4Momentum.px()) + sqr(a4Momentum.py()) + sqr(Mass);
        a4Momentum.setPz(0.5*(aLightConeMomentum - aLightConeE - TransverseMass2/aLightConeMomentum)*(aDirection? 1: -1)); 
        a4Momentum.setE( 0.5*(aLightConeMomentum + aLightConeE + TransverseMass2/aLightConeMomentum));
        Set4Momentum(a4Momentum);
}