genie::utils::gsl::d3Xsec_dOmegaldThetapi Class Reference

#include <GSLXSecFunc.h>

Inheritance diagram for genie::utils::gsl::d3Xsec_dOmegaldThetapi:

Collaboration diagram for genie::utils::gsl::d3Xsec_dOmegaldThetapi:

Public Member Functions
	d3Xsec_dOmegaldThetapi (const XSecAlgorithmI *m, const Interaction *i)
	~d3Xsec_dOmegaldThetapi ()
unsigned int	NDim (void) const
double	DoEval (const double *xin) const
d3Xsec_dOmegaldThetapi *	Clone (void) const
void	SetE_lep (double E_lepton) const

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

Detailed Description

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

genie::utils::gsl::d3Xsec_dOmegaldThetapi A 3-D cross section function (fixed E_nu) Steve Dennis - for the Alvarez-Russo cross-section

Definition at line 395 of file GSLXSecFunc.h.

Constructor & Destructor Documentation

genie::utils::gsl::d3Xsec_dOmegaldThetapi::d3Xsec_dOmegaldThetapi	(	const XSecAlgorithmI *	m,
		const Interaction *	i
	)

Definition at line 899 of file GSLXSecFunc.cxx.

                                                      :
ROOT::Math::IBaseFunctionMultiDim(),
fModel(m),
fInteraction(i),
fElep(-1)
{

}

genie::utils::gsl::d3Xsec_dOmegaldThetapi::~d3Xsec_dOmegaldThetapi

(

)

Definition at line 908 of file GSLXSecFunc.cxx.

{

}

Member Function Documentation

genie::utils::gsl::d3Xsec_dOmegaldThetapi * genie::utils::gsl::d3Xsec_dOmegaldThetapi::Clone

(

void

)

const

Definition at line 989 of file GSLXSecFunc.cxx.

References SetE_lep().

{
  d3Xsec_dOmegaldThetapi * out = new genie::utils::gsl::d3Xsec_dOmegaldThetapi(fModel,fInteraction);
  out->SetE_lep(fElep);
  return out;
}

double genie::utils::gsl::d3Xsec_dOmegaldThetapi::DoEval

(

const double *

xin

)

const

Definition at line 916 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:
//    theta l [rad]
//    phi_l   [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 = fElep;

  double theta_l   = xin[0];
  double phi_l     = xin[1];
  double theta_pi  = xin[2];
  double phi_pi    = 0;

  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 xsec/(1E-38 * units::cm2);
}

unsigned int genie::utils::gsl::d3Xsec_dOmegaldThetapi::NDim

(

void

)

const

Definition at line 912 of file GSLXSecFunc.cxx.

{
  return 3;
}

void genie::utils::gsl::d3Xsec_dOmegaldThetapi::SetE_lep

(

double

E_lepton

)

const

Definition at line 996 of file GSLXSecFunc.cxx.

Referenced by Clone().

{
  fElep = E_lepton;
}

Member Data Documentation

double genie::utils::gsl::d3Xsec_dOmegaldThetapi::fElep

mutableprivate

Definition at line 414 of file GSLXSecFunc.h.

const Interaction* genie::utils::gsl::d3Xsec_dOmegaldThetapi::fInteraction

private

Definition at line 413 of file GSLXSecFunc.h.

const XSecAlgorithmI* genie::utils::gsl::d3Xsec_dOmegaldThetapi::fModel

private

Definition at line 412 of file GSLXSecFunc.h.

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

• GSLXSecFunc.h
• GSLXSecFunc.cxx