G4QGSMFragmentation.cc

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// $Id: G4QGSMFragmentation.cc 100828 2016-11-02 15:25:59Z gcosmo $
//
// -----------------------------------------------------------------------------
//      GEANT 4 class implementation file
//
//      History: first implementation, Maxim Komogorov, 10-Jul-1998
// -----------------------------------------------------------------------------
#include "G4QGSMFragmentation.hh"
#include "G4PhysicalConstants.hh"
#include "Randomize.hh"
#include "G4ios.hh"
#include "G4FragmentingString.hh"
#include "G4DiQuarks.hh"
#include "G4Quarks.hh"

#include "G4Pow.hh"

//#define debug_QGSMfragmentation 

// Class G4QGSMFragmentation 
//****************************************************************************************
 
G4QGSMFragmentation::G4QGSMFragmentation() :
arho(0.5), aphi(0.), an(-0.5), ala(-0.75), aksi(-1.), alft(0.5)
{
  SetStrangenessSuppression(0.41);
  SetDiquarkSuppression(0.25);
  SetDiquarkBreakProbability(0.4);
}

G4QGSMFragmentation::~G4QGSMFragmentation()
{
}

//----------------------------------------------------------------------------------------------------------

G4KineticTrackVector* G4QGSMFragmentation::FragmentString(const G4ExcitedString& theString)
{
  #ifdef debug_QGSMfragmentation
  G4cout<<G4endl<<"QGSM StringFragm: String Mass " <<theString.Get4Momentum().mag()<<" Pz "
                                                   <<theString.Get4Momentum().pz()
        <<"------------------------------------"<<G4endl;
  G4cout<<"String ends Direct "<<theString.GetLeftParton()->GetPDGcode()<<" "
                               <<theString.GetRightParton()->GetPDGcode()<<" "
                               <<theString.GetDirection()<< G4endl;
  G4cout<<"Left  mom "<<theString.GetLeftParton()->Get4Momentum()<<G4endl;
  G4cout<<"Right mom "<<theString.GetRightParton()->Get4Momentum()<<G4endl;
  G4cout<<"Check for Fragmentation "<<G4endl;
  #endif

  // Can no longer modify Parameters for Fragmentation.
  PastInitPhase=true;
    
  // check if string has enough mass to fragment...

  G4KineticTrackVector * LeftVector=LightFragmentationTest(&theString);

  #ifdef debug_QGSMfragmentation
  if ( LeftVector != 0 ) G4cout<<"Non fragmentable - the string is converted to one hadron "<<G4endl;
  #endif

  if ( LeftVector != 0 ) return LeftVector;

  #ifdef debug_QGSMfragmentation
  G4cout<<"The string will be fragmented. "<<G4endl;
  #endif
    
  LeftVector = new G4KineticTrackVector;
  G4KineticTrackVector * RightVector=new G4KineticTrackVector;

  // this should work but its only a semi deep copy. %GF    G4ExcitedString theStringInCMS(theString);
  G4ExcitedString *theStringInCMS=CPExcited(theString);
  G4LorentzRotation toCms=theStringInCMS->TransformToAlignedCms();

  G4bool success=false, inner_sucess=true;
  G4int attempt=0;
  while ( !success && attempt++ < StringLoopInterrupt )  /* Loop checking, 07.08.2015, A.Ribon */
  {
    #ifdef debug_QGSMfragmentation
    G4cout<<"Loop_toFrag "<<theStringInCMS->GetLeftParton()->GetPDGcode()<<" "
                          <<theStringInCMS->GetRightParton()->GetPDGcode()<<" "
                          <<theStringInCMS->GetDirection()<< G4endl;
    #endif

    G4FragmentingString *currentString=new G4FragmentingString(*theStringInCMS);

    std::for_each(LeftVector->begin(), LeftVector->end(), DeleteKineticTrack());
    LeftVector->clear();
    std::for_each(RightVector->begin(), RightVector->end(), DeleteKineticTrack());
    RightVector->clear();
        
    inner_sucess=true;  // set false on failure..
    const G4int maxNumberOfLoops = 1000;
    G4int loopCounter = -1;
    while (! StopFragmenting(currentString) && ++loopCounter < maxNumberOfLoops )   /* Loop checking, 07.08.2015, A.Ribon */
    {  // Split current string into hadron + new string

      #ifdef debug_QGSMfragmentation
      G4cout<<"The string can fragment. "<<G4endl;;
      #endif

      G4FragmentingString *newString=0;  // used as output from SplitUp...
      G4KineticTrack * Hadron=Splitup(currentString,newString);

      if ( Hadron != 0 ) // && IsFragmentable(newString))
      {
        #ifdef debug_QGSMfragmentation
        G4cout<<"Hadron prod at fragm. "<<Hadron->GetDefinition()->GetParticleName()<<G4endl;
        #endif

        if ( currentString->GetDecayDirection() > 0 ) LeftVector->push_back(Hadron);
        else                                          RightVector->push_back(Hadron);

    delete currentString;
    currentString=newString;

      } else {

        #ifdef debug_QGSMfragmentation
        G4cout<<"abandon ... start from the beginning ---------------"<<G4endl;
        #endif

    // abandon ... start from the beginning
    if (newString) delete newString;
    inner_sucess=false;
    break;
      }
    }
    if ( loopCounter >= maxNumberOfLoops ) inner_sucess=false;
              
    // Split current string into 2 final Hadrons
    #ifdef debug_QGSMfragmentation
    G4cout<<"Split remaining string into 2 final hadrons."<<G4endl;
    #endif

    if ( inner_sucess && SplitLast(currentString,LeftVector, RightVector) ) 
    {
      success=true;
    }
    delete currentString;
  } // End of while loop
    
  delete theStringInCMS;
    
  if ( ! success )
  {
    std::for_each(LeftVector->begin(), LeftVector->end(), DeleteKineticTrack());
    LeftVector->clear();
    std::for_each(RightVector->begin(), RightVector->end(), DeleteKineticTrack());
    delete RightVector;
    return LeftVector;
  }
        
  // Join Left- and RightVector into LeftVector in correct order.
  while(!RightVector->empty())  /* Loop checking, 07.08.2015, A.Ribon */
  {
    LeftVector->push_back(RightVector->back());
    RightVector->erase(RightVector->end()-1);
  }
  delete RightVector;

  CalculateHadronTimePosition(theString.Get4Momentum().mag(), LeftVector);

  G4LorentzRotation toObserverFrame(toCms.inverse());

  for(size_t C1 = 0; C1 < LeftVector->size(); C1++)
  {
    G4KineticTrack* Hadron = LeftVector->operator[](C1);
    G4LorentzVector Momentum = Hadron->Get4Momentum();
    Momentum = toObserverFrame*Momentum;
    Hadron->Set4Momentum(Momentum);
    G4LorentzVector Coordinate(Hadron->GetPosition(), Hadron->GetFormationTime());
    Momentum = toObserverFrame*Coordinate;
    Hadron->SetFormationTime(Momentum.e());
    G4ThreeVector aPosition(Momentum.vect());
    Hadron->SetPosition(theString.GetPosition()+aPosition);
   }
   return LeftVector;
}

//----------------------------------------------------------------------------------------------------------

G4double G4QGSMFragmentation::GetLightConeZ(G4double zmin, G4double zmax, G4int PartonEncoding,  
                                            G4ParticleDefinition* pHadron, G4double , G4double )
{    
  #ifdef debug_QGSMfragmentation
  G4cout<<"GetLightConeZ zmin zmax Parton pHadron "<<zmin<<" "<<zmax<<" "<<PartonEncoding<<" "<<pHadron->GetParticleName()<<G4endl;
  #endif

  G4double z;    
  G4double d1, d2, yf;
  G4double invD1(0.),invD2(0.), r1(0.),r2(0.),r12(0.);

  G4int absCode = std::abs( PartonEncoding );
  G4int absHadronCode=std::abs(pHadron->GetPDGEncoding());

  G4int q1, q2, q3;
  q1 = absHadronCode/1000; q2 = (absHadronCode % 1000)/100; q3 = (absHadronCode % 100)/10;

  G4bool StrangeHadron = (q1 == 3) || (q2 == 3) || (q3 == 3);

  if (absCode < 10)
  {                                              // A quark fragmentation ----------------------------
    if(absCode == 1 || absCode == 2) 
    {
      if(absHadronCode < 1000) 
      {                        // Meson  produced
        if( !StrangeHadron )  {d1=2.0;        d2 = -arho + alft;}
        else                  {d1=1.0;        d2 = -aphi + alft;}
      } else                 
      {                        // Baryon produced
        if( !StrangeHadron )  {d1=0.0;        d2 =      arho - 2.0*an        + alft;}
        else                  {d1=0.0;        d2 =  2.0*arho - 2.0*an - aphi + alft;} 
      }
    } 
    else if(absCode == 3)  
    {
      if(absHadronCode < 1000){d1=1.0 - aphi; d2 =  -arho          + alft;}  // Meson  produced s->K + u/d
      else                    {d1=1.0 - aphi; d2 =   arho - 2.0*an + alft;}  // Baryon produced 

    } else throw G4HadronicException(__FILE__, __LINE__, "Unknown PDGencoding in G4QGSMFragmentation::G4LightConeZ");

    #ifdef debug_QGSMfragmentation
    G4cout<<"d1 d2 "<<d1<<" "<<d2<<G4endl;
    #endif

    d1+=1.0; d2+=1.0;

    invD1=1./d1; invD2=1./d2;

    const G4int maxNumberOfLoops = 10000;
    G4int loopCounter = 0;
    do
    {
      r1=G4Pow::GetInstance()->powA(G4UniformRand(),invD1);
      r2=G4Pow::GetInstance()->powA(G4UniformRand(),invD2);
      r12=r1+r2;
      z=r1/r12;
    } while( ( (r12 > 1.0) || !((zmin <= z)&&(z <= zmax))) && ++loopCounter < maxNumberOfLoops );  /* Loop checking, 07.08.2015, A.Ribon */
    if ( loopCounter >= maxNumberOfLoops ) {
      z = 0.5*(zmin + zmax);  // Just a value between zmin and zmax, no physics considerations at all! 
    }

    return z;
  }
  else
  {                                              // A di-quark fragmentation -------------------------
    if(absCode == 1103 || absCode == 2101 || 
       absCode == 2203 || absCode == 2103)
    {
      if(absHadronCode < 1000)                                                // Meson production
      {
        if( !StrangeHadron )  {d1=1.0; d2=     arho - 2.0*an        + alft;} 
        else                  {d1=1.0; d2 = 2.*arho - 2.0*an - aphi + alft;}
      } else {                                                                // Baryon production
        if( !StrangeHadron )  {d1=2.0*(arho - an); d2= -arho         + alft;}
        else                  {d1=2.0*(arho - an); d2 =-aphi         + alft;} 
      }

      #ifdef debug_QGSMfragmentation
      G4cout<<"d1 d2 "<<d1<<" "<<d2<<G4endl;
      #endif

      d1+=1.0; d2+=1.0;
      invD1=1./d1; invD2=1./d2;

      const G4int maxNumberOfLoops = 10000;
      G4int loopCounter = 0;
      do
      {
        r1=G4Pow::GetInstance()->powA(G4UniformRand(),invD1);
        r2=G4Pow::GetInstance()->powA(G4UniformRand(),invD2);
        r12=r1+r2;
        z=r1/r12;
      } while( ( (r12 > 1.0) || !((zmin <= z)&&(z <= zmax))) && ++loopCounter < maxNumberOfLoops );  /* Loop checking, 07.08.2015, A.Ribon */ 
      if ( loopCounter >= maxNumberOfLoops ) {
        z = 0.5*(zmin + zmax);  // Just a value between zmin and zmax, no physics considerations at all! 
      }

      return z;
    }
    else if(absCode == 3101 || absCode == 3103 ||           // For strange d-quarks
            absCode == 3201 || absCode == 3203)
    {
      d2 =  (alft - (2.*ala - arho));
    }
    else
    {
      d2 =  (alft - (2.*aksi - arho));
    }

    const G4int maxNumberOfLoops = 1000;
    G4int loopCounter = 0;
    do  
    {
      z = zmin + G4UniformRand() * (zmax - zmin);
      d1 =  (1. - z);
      yf = G4Pow::GetInstance()->powA(d1, d2);
    } 
    while( (G4UniformRand() > yf) && ++loopCounter < maxNumberOfLoops );  /* Loop checking, 07.08.2015, A.Ribon */   
  }

  return z;
}

//-----------------------------------------------------------------------------------------

G4LorentzVector * G4QGSMFragmentation::SplitEandP(G4ParticleDefinition * pHadron,
                                                  G4FragmentingString * string,
                                                  G4FragmentingString * NewString)
{
  G4double HadronMass = pHadron->GetPDGMass();

  //G4double MinimalStringMass= FragmentationMass(NewString,&G4HadronBuilder::BuildHighSpin);
  G4double MinimalStringMass= FragmentationMass(NewString,&G4HadronBuilder::Build);
  //FragmentationMass(NewString,&G4HadronBuilder::BuildLowSpin); // Uzhi 03.06.2015
  // Uzhi 03.06.2015 It would be well to sample randomly HighSpin

  #ifdef debug_QGSMfragmentation
  G4cout<<"G4QGSMFragmentation::SplitEandP "<<pHadron->GetParticleName()<<G4endl;
  G4cout<<"String 4 mom, String M "<<string->Get4Momentum()<<" "<<string->Mass()<<G4endl;
  G4cout<<"HadM MinimalStringMassLeft StringM hM+sM "<<HadronMass<<" "<<MinimalStringMass<<" "
        <<string->Mass()<<" "<<HadronMass+MinimalStringMass<<G4endl;
  #endif

  if(HadronMass + MinimalStringMass > string->Mass())
  {
    #ifdef debug_QGSMfragmentation
    G4cout<<"Mass of the string is not sufficient to produce the hadron!"<<G4endl;
    #endif
    return 0;
  } // have to start all over!

  // calculate and assign hadron transverse momentum component HadronPx andHadronPy
  G4double StringMT2 = string->MassT2();
  G4double StringMT  = std::sqrt(StringMT2);

  G4LorentzVector String4Momentum = string->Get4Momentum();
  String4Momentum.setPz(0.);
  G4ThreeVector StringPt = String4Momentum.vect();

  G4ThreeVector HadronPt    , RemSysPt;
  G4double      HadronMassT2, ResidualMassT2;

  //...  sample Pt of the hadron
  G4int attempt=0;
  do
  {
    attempt++; if(attempt > StringLoopInterrupt) return 0;

    HadronPt =SampleQuarkPt()  + string->DecayPt(); 
    HadronPt.setZ(0);
    RemSysPt = StringPt - HadronPt;

    HadronMassT2 = sqr(HadronMass) + HadronPt.mag2();
    ResidualMassT2=sqr(MinimalStringMass) + RemSysPt.mag2();

  } while(std::sqrt(HadronMassT2) + std::sqrt(ResidualMassT2) > StringMT);  /* Loop checking, 07.08.2015, A.Ribon */

  //...  sample z to define hadron longitudinal momentum and energy
  //... but first check the available phase space

  G4double Pz2 = (sqr(StringMT2 - HadronMassT2 - ResidualMassT2) -
          4*HadronMassT2 * ResidualMassT2)/4./StringMT2;

  if(Pz2 < 0 ) {return 0;}          // have to start all over!

  //... then compute allowed z region  z_min <= z <= z_max

  G4double Pz = std::sqrt(Pz2);
  G4double zMin = (std::sqrt(HadronMassT2+Pz2) - Pz)/std::sqrt(StringMT2);
  G4double zMax = (std::sqrt(HadronMassT2+Pz2) + Pz)/std::sqrt(StringMT2);

  /*
  G4double DecayQuarkMass2  = sqr(string->GetDecayParton()->GetPDGMass());
  G4double HadronMass2T = sqr(HadronMass) + HadronPt.mag2();
  if (DecayQuarkMass2 + HadronMass2T >= SmoothParam*(string->Mass2()) ) 
    return 0;       // have to start all over!
  //... then compute allowed z region  z_min <= z <= z_max 
  //G4double zMin = HadronMass2T/(string->Mass2());
  //G4double zMax = 1. - DecayQuarkMass2/(string->Mass2());
  */

  if (zMin >= zMax) return 0;       // have to start all over!
    
  G4double z = GetLightConeZ(zMin, zMax, string->GetDecayParton()->GetPDGEncoding(),
                             pHadron, HadronPt.x(), HadronPt.y());      

  //... now compute hadron longitudinal momentum and energy
  // longitudinal hadron momentum component HadronPz

  HadronPt.setZ(0.5* string->GetDecayDirection() * (z * string->LightConeDecay() - 
            HadronMassT2/(z * string->LightConeDecay())));
  G4double HadronE  = 0.5* (z * string->LightConeDecay() + 
                    HadronMassT2/(z * string->LightConeDecay()));

  G4LorentzVector * a4Momentum= new G4LorentzVector(HadronPt,HadronE);

  #ifdef debug_QGSMfragmentation
  G4cout<<"string->GetDecayDirection() string->LightConeDecay() "
        <<string->GetDecayDirection()<<" "<<string->LightConeDecay()<<G4endl;
  G4cout<<"HadronPt,HadronE "<<HadronPt<<" "<<HadronE<<G4endl;
  //G4cout<<"String4Momentum "<<String4Momentum<<G4endl;
  //G4int Uzhi; G4cin>>Uzhi;
  G4cout<<"Out of QGSM SplitEandP "<<G4endl;
  #endif

  return a4Momentum;
}

//-----------------------------------------------------------------------------------------

G4bool G4QGSMFragmentation::SplitLast(G4FragmentingString * string,
                      G4KineticTrackVector * LeftVector,
                          G4KineticTrackVector * RightVector)
{
  //... perform last cluster decay

  G4ThreeVector ClusterVel =string->Get4Momentum().boostVector();
  G4double ResidualMass    =string->Mass(); 

  #ifdef debug_QGSMfragmentation
  G4cout<<"Split last-----------------------------------------"<<G4endl;
  G4cout<<"StrMass "<<ResidualMass<<" q's "
        <<string->GetLeftParton()->GetParticleName()<<" "
        <<string->GetRightParton()->GetParticleName()<<G4endl;
  #endif

  G4double ClusterMassCut = ClusterMass;            // Taken from G4VLongitudinalStringDecay
  G4int cClusterInterrupt = 0;
  G4ParticleDefinition * LeftHadron, * RightHadron;
  const G4int maxNumberOfLoops = 1000;
  G4int loopCounter = 0;
  do
  {
    if (cClusterInterrupt++ >= ClusterLoopInterrupt)
    {
      return false;
    }

    G4ParticleDefinition * quark = NULL;
    string->SetLeftPartonStable(); // to query quark contents..

    if (string->DecayIsQuark() && string->StableIsQuark() ) 
    {
      //... there are quarks on cluster ends
      LeftHadron= QuarkSplitup(string->GetLeftParton(), quark);
    } else {
      //... there is a Diquark on cluster ends
      G4int IsParticle;
      if ( string->StableIsQuark() ) {
    IsParticle=(string->GetLeftParton()->GetPDGEncoding()>0) ? -1 : +1; 
      } else {
    IsParticle=(string->GetLeftParton()->GetPDGEncoding()>0) ? +1 : -1;
      }

      pDefPair QuarkPair = CreatePartonPair(IsParticle,false);  // no diquarks wanted
      quark = QuarkPair.second;
      LeftHadron=hadronizer->Build(QuarkPair.first, string->GetLeftParton());
    }

    RightHadron = hadronizer->Build(string->GetRightParton(), quark);

    //... repeat procedure, if mass of cluster is too low to produce hadrons
    //... ClusterMassCut = 0.15*GeV model parameter
    if ( quark->GetParticleSubType()== "quark" ) {ClusterMassCut = 0.;}
    else {ClusterMassCut = ClusterMass;}
  
  } while ( (ResidualMass <= LeftHadron->GetPDGMass() + RightHadron->GetPDGMass() + ClusterMassCut)
            && ++loopCounter < maxNumberOfLoops );  /* Loop checking, 07.08.2015, A.Ribon */

  if ( loopCounter >= maxNumberOfLoops ) {
    return false;
  }

  //... compute hadron momenta and energies   
  G4LorentzVector  LeftMom, RightMom;
  G4ThreeVector    Pos;
  Sample4Momentum(&LeftMom , LeftHadron->GetPDGMass() , 
                  &RightMom, RightHadron->GetPDGMass(), ResidualMass);
  LeftMom.boost(ClusterVel);
  RightMom.boost(ClusterVel);

  #ifdef debug_QGSMfragmentation
  G4cout<<LeftHadron->GetParticleName()<<" "<<RightHadron->GetParticleName()<<G4endl;
  G4cout<<"Left  Hadrom P M "<<LeftMom<<" "<<LeftMom.mag()<<G4endl;
  G4cout<<"Right Hadrom P M "<<RightMom<<" "<<RightMom.mag()<<G4endl;
  #endif

  LeftVector->push_back(new G4KineticTrack(LeftHadron, 0, Pos, LeftMom));
  RightVector->push_back(new G4KineticTrack(RightHadron, 0, Pos, RightMom));

  return true;
}

//----------------------------------------------------------------------------------------------------------

G4bool G4QGSMFragmentation::IsFragmentable(const G4FragmentingString * const string)
{
  return sqr(FragmentationMass(string)+MassCut) < string->Mass2();
}

//----------------------------------------------------------------------------------------------------------

G4bool G4QGSMFragmentation::StopFragmenting(const G4FragmentingString * const string)
{
  return sqr(FragmentationMass(string,&G4HadronBuilder::BuildHighSpin)+MassCut) >
         string->Get4Momentum().mag2();
}

//----------------------------------------------------------------------------------------------------------

void G4QGSMFragmentation::Sample4Momentum(G4LorentzVector* Mom    , G4double Mass    , 
                                          G4LorentzVector* AntiMom, G4double AntiMass, G4double InitialMass) 
{
  G4double r_val = sqr(InitialMass*InitialMass - Mass*Mass - AntiMass*AntiMass) - sqr(2.*Mass*AntiMass);
  G4double Pabs = (r_val > 0.)? std::sqrt(r_val)/(2.*InitialMass) : 0;

  //... sample unit vector       
  G4double pz = 1. - 2.*G4UniformRand();  
  G4double st     = std::sqrt(1. - pz * pz)*Pabs;
  G4double phi    = 2.*pi*G4UniformRand();
  G4double px = st*std::cos(phi);
  G4double py = st*std::sin(phi);
  pz *= Pabs;
    
  Mom->setPx(px); Mom->setPy(py); Mom->setPz(pz);
  Mom->setE(std::sqrt(Pabs*Pabs + Mass*Mass));

  AntiMom->setPx(-px); AntiMom->setPy(-py); AntiMom->setPz(-pz);
  AntiMom->setE (std::sqrt(Pabs*Pabs + AntiMass*AntiMass));
}
    
//*********************************************************************************************
// Uzhi June 2014 Insert from G4ExcitedStringDecay.cc
//-----------------------------------------------------------------------------

G4ParticleDefinition *G4QGSMFragmentation::DiQuarkSplitup(G4ParticleDefinition* decay,
                                                          G4ParticleDefinition *&created)
{
  //... can Diquark break or not?
  if (G4UniformRand() < DiquarkBreakProb ){
    //... Diquark break

    G4int stableQuarkEncoding = decay->GetPDGEncoding()/1000;
    G4int decayQuarkEncoding = (decay->GetPDGEncoding()/100)%10;

    if (G4UniformRand() < 0.5)
    {
      G4int Swap = stableQuarkEncoding;
      stableQuarkEncoding = decayQuarkEncoding;
      decayQuarkEncoding = Swap;
    }

    G4int IsParticle=(decayQuarkEncoding>0) ? -1 : +1; // if we have a quark, we need antiquark)

    G4double StrSup=GetStrangeSuppress();  // for changing s-sbar production
    StrangeSuppress=0.41;                          // was 0.47
    pDefPair QuarkPair = CreatePartonPair(IsParticle,false);  // no diquarks wanted
    StrangeSuppress=StrSup;

    //... Build new Diquark
    G4int QuarkEncoding=QuarkPair.second->GetPDGEncoding();
    G4int i10  = std::max(std::abs(QuarkEncoding), std::abs(stableQuarkEncoding));
    G4int i20  = std::min(std::abs(QuarkEncoding), std::abs(stableQuarkEncoding));
    G4int spin = (i10 != i20 && G4UniformRand() <= 0.5)? 1 : 3;
    G4int NewDecayEncoding = -1*IsParticle*(i10 * 1000 + i20 * 100 + spin);
    created = FindParticle(NewDecayEncoding);
    G4ParticleDefinition * decayQuark=FindParticle(decayQuarkEncoding);
    G4ParticleDefinition * had=hadronizer->Build(QuarkPair.first, decayQuark);

    return had;
    //return hadronizer->Build(QuarkPair.first, decayQuark);

  } else {
    //... Diquark does not break

    G4int IsParticle=(decay->GetPDGEncoding()>0) ? +1 : -1;  // if we have a diquark, we need quark)
    G4double StrSup=GetStrangeSuppress();  // for changing s-sbar production
    StrangeSuppress=0.41; //0.41; 0.47
    pDefPair QuarkPair = CreatePartonPair(IsParticle,false);  // no diquarks wanted
    StrangeSuppress=StrSup;

    created = QuarkPair.second;

    G4ParticleDefinition * had=hadronizer->Build(QuarkPair.first, decay);
    return had;
    //return G4ParticleDefinition * had=hadronizer->Build(QuarkPair.first, decay);
  }
}