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);
        
        if(Random::shoot()<0.5) PhaseSpaceGenerator::generateBiased(sqrtS, list, 0, angularSlope);
        else PhaseSpaceGenerator::generateBiased(sqrtS, list, 1, angularSlope);
        
        
        fs->addModifiedParticle(delta);
        fs->addModifiedParticle(nucleon);
        fs->addCreatedParticle(kaon);
        
    }
}