#include <GSLXSecFunc.h>

Inheritance diagram for genie::utils::gsl::d5XSecAR:

Collaboration diagram for genie::utils::gsl::d5XSecAR:

Public Member Functions
	d5XSecAR (const XSecAlgorithmI m, const Interaction i)

	~d5XSecAR ()

unsigned int	NDim (void) const

double	DoEval (const double *xin) const

ROOT::Math::IBaseFunctionMultiDim *	Clone (void) const

void	SetFlip (bool b)

Private Attributes
const XSecAlgorithmI *	fModel

const Interaction *	fInteraction

bool	flip

Detailed Description

Definition at line 325 of file GSLXSecFunc.h.

Constructor & Destructor Documentation

genie::utils::gsl::d5XSecAR::d5XSecAR	(	const XSecAlgorithmI *	m,
		const Interaction *	i
	)

Definition at line 598 of file GSLXSecFunc.cxx.

                                                       :
 ROOT::Math::IBaseFunctionMultiDim(),
 fModel(m),
 fInteraction(i),
 flip(false)
 {
 
 }

genie::utils::gsl::d5XSecAR::~d5XSecAR ( )

Definition at line 607 of file GSLXSecFunc.cxx.

608 {

609 }

Member Function Documentation

ROOT::Math::IBaseFunctionMultiDim * genie::utils::gsl::d5XSecAR::Clone ( void ) const

Definition at line 689 of file GSLXSecFunc.cxx.

 {
   return
     new genie::utils::gsl::d5XSecAR(fModel,fInteraction);
 }

double genie::utils::gsl::d5XSecAR::DoEval ( const double * xin ) const

Definition at line 615 of file GSLXSecFunc.cxx.

References genie::constants::kNucleonMass, genie::constants::kPi0Mass, genie::constants::kPionMass, genie::kRfLab, genie::Range1D_t::max, genie::utils::kinematics::Q2(), genie::Kinematics::SetFSLeptonP4(), genie::Kinematics::SetHadSystP4(), genie::Kinematics::Setx(), genie::Kinematics::Sety(), and genie::utils::kinematics::UpdateWQ2FromXY().

 {
 // inputs:
 //    x [-]
 //    y [-]
 // outputs:
 //   differential cross section [10^-38 cm^2]
 //
 
   Kinematics * kinematics = fInteraction->KinePtr();
   const TLorentzVector * P4_nu = fInteraction->InitStatePtr()->GetProbeP4(kRfLab);
   double E_nu       = P4_nu->E();
 
   double E_l       = xin[0];
   double theta_l   = xin[1];
   double phi_l     = xin[2];
   double theta_pi  = xin[3];
   double phi_pi    = xin[4];
 
   double E_pi= E_nu-E_l;
 
   double y = E_pi/E_nu;
 
   double m_l = fInteraction->FSPrimLepton()->Mass();
   if (E_l < m_l) {
     return 0.;
   }
 
   double m_pi;
   if ( fInteraction->ProcInfo().IsWeakCC() ) {
     m_pi = constants::kPionMass;
   }
   else {
     m_pi = constants::kPi0Mass;
   }
 
 
   double p_l = TMath::Sqrt(E_l*E_l - m_l*m_l);
   TVector3 lepton_3vector = TVector3(0,0,0);
   lepton_3vector.SetMagThetaPhi(p_l,theta_l,phi_l);
   TLorentzVector P4_lep    = TLorentzVector(lepton_3vector , E_l );
 
   double p_pi = TMath::Sqrt(E_pi*E_pi - m_pi*m_pi);
   TVector3 pion_3vector = TVector3(0,0,0);
   pion_3vector.SetMagThetaPhi(p_pi,theta_pi,phi_pi);
   TLorentzVector P4_pion   = TLorentzVector(pion_3vector   , E_pi);
 
   double Q2 = -(*P4_nu-P4_lep).Mag2();
 
   double x = Q2/(2*E_pi*constants::kNucleonMass);
 
   Range1D_t xlim = fInteraction->PhaseSpace().XLim();
 
   if ( x <  xlim.min || x > xlim.max ) {
     return 0.;
   }
 
   kinematics->Setx(x);
   kinematics->Sety(y);
   kinematics::UpdateWQ2FromXY(fInteraction);
 
   kinematics->SetFSLeptonP4(P4_lep );
   kinematics->SetHadSystP4 (P4_pion); // use Hadronic System variable to store pion momentum
 
   double xsec = fModel->XSec(fInteraction);
   if (xsec>0 && flip) {
     xsec = xsec*-1.0;
   }
   delete P4_nu;
   //return xsec/(1E-38 * units::cm2);
   return xsec;
 }