#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

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

Definition at line 104 of file BezrukovBugaevModel.cxx.

References genie::units::A, fA, and fE.

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

gsl::BezrukovBugaevIntegrand::~BezrukovBugaevIntegrand ( )

Definition at line 111 of file BezrukovBugaevModel.cxx.

 {
 
 }

Member Function Documentation

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

Definition at line 172 of file BezrukovBugaevModel.cxx.

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

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

Definition at line 121 of file BezrukovBugaevModel.cxx.

References a, genie::constants::kAem, genie::constants::kMuonMass2, genie::constants::kPi, and genie::units::ub.

 {
 // 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;
 }