#include <BezrukovBugaevModel.h>

Inheritance diagram for genie::mueloss::gsl::BezrukovBugaevIntegrand:

Collaboration diagram for genie::mueloss::gsl::BezrukovBugaevIntegrand:

Public Member Functions
	BezrukovBugaevIntegrand (double E, double A)
	~BezrukovBugaevIntegrand ()
unsigned int	NDim (void) const
double	DoEval (double xin) const
ROOT::Math::IBaseFunctionOneDim *	Clone (void) const

Private Attributes
double	fE
double	fA

Detailed Description

Definition at line 69 of file BezrukovBugaevModel.h.

Constructor & Destructor Documentation

◆ BezrukovBugaevIntegrand()

gsl::BezrukovBugaevIntegrand::BezrukovBugaevIntegrand	(	double	E,
		double	A )

Definition at line 104 of file BezrukovBugaevModel.cxx.

                                                                      :
ROOT::Math::IBaseFunctionOneDim()
{
  fE = E;
  fA = A;
}

References fA, and fE.

◆ ~BezrukovBugaevIntegrand()

gsl::BezrukovBugaevIntegrand::~BezrukovBugaevIntegrand ( )

Definition at line 111 of file BezrukovBugaevModel.cxx.

{
 
}

Member Function Documentation

◆ Clone()

ROOT::Math::IBaseFunctionOneDim * gsl::BezrukovBugaevIntegrand::Clone ( void ) const

Definition at line 172 of file BezrukovBugaevModel.cxx.

{
  return new gsl::BezrukovBugaevIntegrand(fE, fA);
}

References fA, and fE.

◆ DoEval()

double gsl::BezrukovBugaevIntegrand::DoEval ( double xin ) const

Definition at line 121 of file BezrukovBugaevModel.cxx.

{
// Returns v*(ds/dv)
 
  double v = xin; // v, the fraction of energy transfered to the photon
 
  if (! (v >0)) return 0;
  if (   v >1)  return 0;
  if (! (fE>0)) return 0;
 
  double a    = kAem;
  double pi   = kPi;
  double mmu2 = kMuonMass2;
  double v2   = TMath::Power(v,2.);
  double t    = mmu2 *v2/(1-v);
  double k    = 1. - 2./v + 2./v2;
  double A13  = TMath::Power(fA,1./3.);
  double M1_2 = 0.54; // m1^2 in photonuclear diff. xsec formula (in GeV^2)
  double M2_2 = 1.80; // m2^2 in photonuclear diff. xsec formula (in GeV^2)
  double M1_2_t = M1_2 / t;
  double M2_2_t = M2_2 / t;
  double mmu2_t = mmu2 / t;
  double d      = M1_2 / (t + M1_2);
 
  // Calculate the cross section (in ub) for photonuclear interaction
  double Ep   = v*fE; // photon energy (GeV)
  double loge = TMath::Log(0.0213*Ep); // factor 0.0213 has units of GeV^-1
  double sig  = 114.3 + 1.647 * loge*loge; // in ub
 
  // Calculate the factor G (dimensionless) appearing in the differential
  // photonuclear interaction cross section
  double x   = 0.00282*A13*sig;  // factor 0.00282 has units of ub^-1
  double x2  = x*x;
  double x3  = x2*x;
  double G   = 3*(0.5*x2 - 1. + (1.+x)*TMath::Exp(-x)) /x3;
 
  // Calculate the differential cross section ds/dv for muon nuclear
  // interaction based on the Bezrukov-Bugaev formula.
  double bbA = 0.5*(a/pi) * fA * sig * v;
  double bbB = 0.75*G     * ( k*TMath::Log(1.+M1_2_t) - k*d - 2.*mmu2_t );
  double bbC = 0.25       * ( k*TMath::Log(1.+M2_2_t) - 2.*mmu2_t );
  double bbD = 0.5*mmu2_t * ( 0.75*G*d + 0.25*M2_2_t*TMath::Log(1.+1./M2_2_t) );
 
  double ds_dv  = bbA*(bbB+bbC+bbD); // in um (microbarns)
  double vds_dv = v*ds_dv;
 
  vds_dv *= units::ub; // ub -> GeV^-2
  return vds_dv;
}