Nucleus2gamma2 Class Reference

Inheritance diagram for Nucleus2gamma2:

Public Member Functions
	Nucleus2gamma2 (int idBeamIn)
void	xfUpdate (int, double x, double) override

Detailed Description

Definition at line 81 of file Pythia8Hadronizer.cc.

Constructor & Destructor Documentation

Nucleus2gamma2()

Nucleus2gamma2::Nucleus2gamma2 ( int  idBeamIn )

inline

Definition at line 84 of file Pythia8Hadronizer.cc.

: Pythia8::PDF(idBeamIn) {}

Member Function Documentation

xfUpdate()

void Nucleus2gamma2::xfUpdate ( int  , double  x, double    )

inlineoverride

Definition at line 87 of file Pythia8Hadronizer.cc.

References ReggeGribovPartonMC_AdvancedParameters_cfi::bmin, callgraph::m2, M_PI, L1TauEmu::pow2(), CosmicsPD_Skims::radius, mathSSE::sqrt(), x, and protons_cff::xi.

                                                {
    // lead
    double radius = 0;  // radius in [fm]
    double z = 0;
    if (idBeam == 1000822080) {
      radius = 6.636;
      z = 82;
    }
    // oxygen
    else if (idBeam == 80160) {
      radius = 3.02;
      z = 8;
    }

    // Minimum impact parameter (~2*radius) [fm].
    double bmin = 2 * radius;

    // Per-nucleon mass for lead.
    double m2 = pow2(0.9314);
    double alphaEM = 0.007297353080;
    double hbarc = 0.197;
    double xi = x * sqrt(m2) * bmin / hbarc;
    double bK0 = besselK0(xi);
    double bK1 = besselK1(xi);
    double intB = xi * bK1 * bK0 - 0.5 * pow2(xi) * (pow2(bK1) - pow2(bK0));
    xgamma = 2. * alphaEM * pow2(z) / M_PI * intB;
  }