genie::utils::gsl::d4Xsec_dEldThetaldOmegapi Class Reference

#include <GSLXSecFunc.h>

Inheritance diagram for genie::utils::gsl::d4Xsec_dEldThetaldOmegapi:

Collaboration diagram for genie::utils::gsl::d4Xsec_dEldThetaldOmegapi:

Public Member Functions
	d4Xsec_dEldThetaldOmegapi (const XSecAlgorithmI *m, const Interaction *i)
	~d4Xsec_dEldThetaldOmegapi ()
unsigned int	NDim (void) const
double	DoEval (const double *xin) const
ROOT::Math::IBaseFunctionMultiDim *	Clone (void) const
double	GetFactor () const
void	SetFactor (double factor)

Private Attributes
const XSecAlgorithmI *	fModel
const Interaction *	fInteraction
double	fFactor

Detailed Description

.....................................................................................

genie::utils::gsl::d4Xsec_dEldThetaldOmegapi A 4-D cross section function (fixed E_nu) DANIEL - for the Alvarez-Russo cross-section

Definition at line 370 of file GSLXSecFunc.h.

Constructor & Destructor Documentation

genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::d4Xsec_dEldThetaldOmegapi	(	const XSecAlgorithmI *	m,
		const Interaction *	i
	)

Definition at line 796 of file GSLXSecFunc.cxx.

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

}

genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::~d4Xsec_dEldThetaldOmegapi

(

)

Definition at line 804 of file GSLXSecFunc.cxx.

{

}

Member Function Documentation

ROOT::Math::IBaseFunctionMultiDim * genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::Clone

(

void

)

const

Definition at line 885 of file GSLXSecFunc.cxx.

{
  return
    new genie::utils::gsl::d4Xsec_dEldThetaldOmegapi(fModel,fInteraction);
}

double genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::DoEval

(

const double *

xin

)

const

Definition at line 812 of file GSLXSecFunc.cxx.

References genie::units::cm2, genie::constants::kNucleonMass, genie::constants::kPi0Mass, genie::constants::kPionMass, genie::kPSElOlTpifE, 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:
//    El [GeV]
//    theta l [rad]
//    theta pi [rad]
//    phi pi [rad]
// 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     = 0.0;
  double theta_pi  = xin[2];
  double phi_pi    = xin[3];

  double sin_theta_l  = TMath::Sin(theta_l);
  double sin_theta_pi = TMath::Sin(theta_pi);

  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

  delete P4_nu;

  double xsec = sin_theta_l * sin_theta_pi * fModel->XSec(fInteraction,kPSElOlTpifE);
  return fFactor * xsec/(1E-38 * units::cm2);
}

double genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::GetFactor

(

void

)

const

Definition at line 894 of file GSLXSecFunc.cxx.

{
  return fFactor;
}

unsigned int genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::NDim

(

void

)

const

Definition at line 808 of file GSLXSecFunc.cxx.

{
  return 4;
}

void genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::SetFactor

(

double

factor

)

Definition at line 890 of file GSLXSecFunc.cxx.

Referenced by genie::COHKinematicsGenerator::MaxXSec_AlvarezRuso().

{
  fFactor = factor;
}

Member Data Documentation

double genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::fFactor

private

Definition at line 387 of file GSLXSecFunc.h.

const Interaction* genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::fInteraction

private

Definition at line 386 of file GSLXSecFunc.h.

const XSecAlgorithmI* genie::utils::gsl::d4Xsec_dEldThetaldOmegapi::fModel

private

Definition at line 385 of file GSLXSecFunc.h.

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The documentation for this class was generated from the following files:

• GSLXSecFunc.h
• GSLXSecFunc.cxx