source: trunk/source/processes/hadronic/models/chiral_inv_phase_space/body/src/G4QPomeron.cc @ 836

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// $Id: G4QPomeron.cc,v 1.2 2006/12/12 11:02:22 mkossov Exp $
// GEANT4 tag $Name:  $
//
// ------------------------------------------------------------
//      GEANT 4 class implementation file
//
//      ---------------- G4QPomeron ----------------
//      by Mikhail Kossov Oct, 2006
//      class for a Pomeron used by Parton String Models
//   For comparison mirror member functions are taken from G4 class:
//   G4PomeronCrossSection
// -----------------------------------------------------------------

#include "G4QPomeron.hh"

G4QPomeron::G4QPomeron(G4int PDG)
{
         pomeron_Alpha=         1.0808;
         pomeron_Alphaprime =   0.25/GeV/GeV;     
  pomeron_Gamma_Hard = 0.0002/GeV/GeV;
  pomeron_Alpha_Hard = 1.47;
  G4int aP = std::abs(PDG);
  if     (aP==2212||aP==2112)                   InitForNucleon();
  else if(PDG==111||aP==211)                    InitForPion();
  else if(PDG==130||PDG==310||aP==311||aP==321) InitForKaon();
  else if(PDG==22)                              InitForGamma();
  else if(aP==3122||aP==3222||aP==3212||aP==3112||aP==3322||aP==3312||aP==3334)
                                                InitForNucleon();
  else
                {
    G4cout<<"-Warning-G4QPomeron is initialised for PDGCode="<<PDG<<" as a pion"<<G4endl;
    InitForPion();
  }
}

G4double G4QPomeron::GetCutPomeronProbability(const G4double s,const G4double imp2,
                                              const G4int nPom)
{
         G4double f=1; if(nPom>1) for(G4int i=2; i<= nPom; i++) f*=i; // Calculate factorial
  G4double e=Eikonal(s,imp2); e+=e;                            // Doubled Eikonal
        return std::exp(-e)*std::pow(e,nPom)/pomeron_C/f;
}

void G4QPomeron::InitForNucleon()
{
  // pomeron_S=         3.0*GeV*GeV;  
         pomeron_S=             2.7*GeV*GeV;
  //    pomeron_Gamma=          2.16/GeV/GeV;      // ? M.K.
  //    pomeron_Gamma=          3.96/GeV/GeV;      // ? M.K.
         pomeron_Gamma   =      (2.6+3.96)/GeV/GeV; // ? M.K.
         pomeron_C       =      1.4;
         pomeron_Rsquare =      3.56/GeV/GeV;
         /////pomeron_Alpha=            0.9808;          // This is very strange M.K. (was in GHAD QGSM)
  // If pomeron_Gamma_Hard!=0 to fit total pp XS use pomeron_Gamma_Soft=2.35/GeV/GeV ? M.K.
}

void G4QPomeron::InitForPion()
{
         pomeron_S       =      1.5*GeV*GeV;
  //pomeron_Gamma =     1.46/GeV/GeV;  // ? M.K.
         pomeron_Gamma   =      2.17/GeV/GeV;  // ? M.K.
         pomeron_C       =      1.6;
         pomeron_Rsquare =      2.36/GeV/GeV;
}

void G4QPomeron::InitForKaon()
{
         pomeron_S       =      2.3*GeV*GeV;
  //pomeron_Gamma =     1.31/GeV/GeV;  // ? M.K.
         pomeron_Gamma   = 1.92/GeV/GeV;  // ? M.K.
         pomeron_C       =      1.8;
         pomeron_Rsquare =      1.96/GeV/GeV;
}

void G4QPomeron::InitForGamma()
{
         pomeron_S       =      1.7*GeV*GeV;
  //pomeron_Gamma =             1.42/GeV/GeV; // ? M.K.
         pomeron_Gamma   =      2.07/GeV/GeV;  // ? M.K.
         pomeron_C       =      1.7;
         pomeron_Rsquare =      2.16/GeV/GeV;
}

G4double G4QPomeron::Expand(G4double z)
{

        G4double sum=1.;
        G4double current=1.;
        for(G4int j=2; j<21; j++)
        {
                 current *= -z*(j-1)/j/j;
                 sum+=current;
        }
        return sum;
}