G4INCLNDeltaToDeltaLKChannel.cc

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//
// INCL++ intra-nuclear cascade model
// Alain Boudard, CEA-Saclay, France
// Joseph Cugnon, University of Liege, Belgium
// Jean-Christophe David, CEA-Saclay, France
// Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
// Sylvie Leray, CEA-Saclay, France
// Davide Mancusi, CEA-Saclay, France
//
#define INCLXX_IN_GEANT4_MODE 1

#include "globals.hh"

#include "G4INCLNDeltaToDeltaLKChannel.hh"
#include "G4INCLKinematicsUtils.hh"
#include "G4INCLBinaryCollisionAvatar.hh"
#include "G4INCLRandom.hh"
#include "G4INCLGlobals.hh"
#include "G4INCLLogger.hh"
#include <algorithm>
#include "G4INCLPhaseSpaceGenerator.hh"

namespace G4INCL {
  
  const G4double NDeltaToDeltaLKChannel::angularSlope = 2.;
  
  NDeltaToDeltaLKChannel::NDeltaToDeltaLKChannel(Particle *p1, Particle *p2)
    : particle1(p1), particle2(p2)
    {}
  
  NDeltaToDeltaLKChannel::~NDeltaToDeltaLKChannel(){}
  
  G4double NDeltaToDeltaLKChannel::sampleDeltaMass(G4double ecm) {
    const G4double maxDeltaMass = ecm - ParticleTable::effectiveLambdaMass - ParticleTable::effectiveKaonMass - 1.0;
    const G4double maxDeltaMassRndm = std::atan((maxDeltaMass-ParticleTable::effectiveDeltaMass)*2./ParticleTable::effectiveDeltaWidth);
    const G4double deltaMassRndmRange = maxDeltaMassRndm - ParticleTable::minDeltaMassRndm;
// assert(deltaMassRndmRange>0.);

    G4double y=ecm*ecm;
    G4double q2=(y-1.157776E6)*(y-6.4E5)/y/4.0; // 1.157776E6 = 1076^2 = (mNucleon + mPion)^2, 6.4E5 = 800^2 = (mNucleon - mPion)^2
    G4double q3=std::pow(std::sqrt(q2), 3.);
    const G4double f3max=q3/(q3+5.832E6); // 5.832E6 = 180^3 = ???^3
    G4double x;

    G4int nTries = 0;
    G4bool success = false;
    while(!success) { /* Loop checking, 10.07.2015, D.Mancusi */
      if(++nTries >= 100000) {
        INCL_WARN("NDeltaToDeltaLKChannel::sampleDeltaMass loop was stopped because maximum number of tries was reached. Minimum delta mass "
              << ParticleTable::minDeltaMass << " MeV with CM energy " << ecm << " MeV may be unphysical." << '\n');
        return ParticleTable::minDeltaMass;
      }
      
      G4double rndm = ParticleTable::minDeltaMassRndm + Random::shoot() * deltaMassRndmRange;
      y = std::tan(rndm);
      x = ParticleTable::effectiveDeltaMass + 0.5*ParticleTable::effectiveDeltaWidth*y;
// assert(x>=ParticleTable::minDeltaMass && ecm >= x + ParticleTable::effectiveLambdaMass + ParticleTable::effectiveKaonMass + 1.0);
      
      // generation of the delta mass with the penetration factor
      // (see prc56(1997)2431)
      y=x*x;
      q2=(y-1.157776E6)*(y-6.4E5)/y/4.0; // 1.157776E6 = 1076^2 = (mNucleon + mPion)^2, 6.4E5 = 800^2 = (mNucleon - mPion)^2
      q3=std::pow(std::sqrt(q2), 3.);
      const G4double f3=q3/(q3+5.832E6); // 5.832E6 = 180^3 = ???^3
      rndm = Random::shoot();
      if (rndm*f3max < f3)
      success = true;
    }
    return x;
  }
  
  void NDeltaToDeltaLKChannel::fillFinalState(FinalState *fs) {
        // D++ p -> L K+ D++ (4)
        //
        // D++ n -> L K+ D+  (3)
        // D++ n -> L K0 D++ (4)
        //
        // D+  p -> L K0 D++ (3)
        // D+  p -> L K+ D+  (2)
        //
        // D+  n -> L K+ D0  (4)
        // D+  n -> L K0 D+  (2)
        
        Particle *delta;
        Particle *nucleon;
        
        if (particle1->isResonance()) {
            delta = particle1;
            nucleon = particle2;
        }
        else {
            delta = particle2;
            nucleon = particle1;
        }
    
    
    const G4double sqrtS = KinematicsUtils::totalEnergyInCM(particle1, particle2);
    
    const G4int iso = ParticleTable::getIsospin(particle1->getType()) + ParticleTable::getIsospin(particle2->getType());
    const G4int iso_d = ParticleTable::getIsospin(delta->getType());
    const G4double rdm = Random::shoot();
    
/*    const G4double m1 = particle1->getMass();
    const G4double m2 = particle2->getMass();
    const G4double pLab = KinematicsUtils::momentumInLab(particle1, particle2);*/
    
    ParticleType KaonType;
    ParticleType DeltaType;
    nucleon->setType(Lambda);
    
    if(std::abs(iso) == 4){// D++ p
      KaonType = ParticleTable::getKaonType(iso/4);
      DeltaType = ParticleTable::getDeltaType(3*iso/4);
    }
    else if(iso == 0){// D+  n
      if(rdm*3 < 2){
        KaonType = ParticleTable::getKaonType(iso_d);
        DeltaType = ParticleTable::getDeltaType(-iso_d);
      }
      else{
        KaonType = ParticleTable::getKaonType(-iso_d);
        DeltaType = ParticleTable::getDeltaType(iso_d);
      }
    }
    else if(ParticleTable::getIsospin(particle1->getType()) == ParticleTable::getIsospin(particle2->getType())){// D+  p
      if(rdm*5 < 3){
        KaonType = ParticleTable::getKaonType(-iso/2);
        DeltaType = ParticleTable::getDeltaType(3*iso/2);
      }
      else{
        KaonType = ParticleTable::getKaonType(iso/2);
        DeltaType = ParticleTable::getDeltaType(iso/2);
      }
    }
    else{// D++ n 
      if(rdm*7 < 3){
        KaonType = ParticleTable::getKaonType(iso/2);
        DeltaType = ParticleTable::getDeltaType(iso/2);
      }
      else{
        KaonType = ParticleTable::getKaonType(-iso/2);
        DeltaType = ParticleTable::getDeltaType(3*iso/2);
      }
    }
    
    delta->setType(DeltaType);
    delta->setMass(sampleDeltaMass(sqrtS));
    
    ParticleList list;
    list.push_back(delta);
    list.push_back(nucleon);
    const ThreeVector &rcol = nucleon->getPosition();
    const ThreeVector zero;
    Particle *kaon = new Particle(KaonType,zero,rcol);
    list.push_back(kaon);
    
    PhaseSpaceGenerator::generateBiased(sqrtS, list, 0, angularSlope);
    
    
    fs->addModifiedParticle(delta);
    fs->addModifiedParticle(nucleon);
    fs->addCreatedParticle(kaon);
    
  }
}