Differential cross section for v+N / vbar+N elastic scattering.
Is a concrete implementation of the XSecAlgorithmI interface.
. More...

#include <AhrensNCELPXSec.h>

Inheritance diagram for genie::AhrensNCELPXSec:

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Collaboration diagram for genie::AhrensNCELPXSec:

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Public Member Functions
	AhrensNCELPXSec ()
	AhrensNCELPXSec (string config)
virtual	~AhrensNCELPXSec ()
double	XSec (const Interaction *i, KinePhaseSpace_t k) const
	Compute the cross section for the input interaction.
double	Integral (const Interaction *i) const
bool	ValidProcess (const Interaction *i) const
	Can this cross section algorithm handle the input process?
void	Configure (const Registry &config)
void	Configure (string param_set)
Public Member Functions inherited from genie::XSecAlgorithmI
virtual	~XSecAlgorithmI ()
virtual bool	ValidKinematics (const Interaction *i) const
	Is the input kinematical point a physically allowed one?
Public Member Functions inherited from genie::Algorithm
virtual	~Algorithm ()
virtual void	FindConfig (void)
virtual const Registry &	GetConfig (void) const
Registry *	GetOwnedConfig (void)
virtual const AlgId &	Id (void) const
	Get algorithm ID.
virtual AlgStatus_t	GetStatus (void) const
	Get algorithm status.
virtual bool	AllowReconfig (void) const
virtual AlgCmp_t	Compare (const Algorithm *alg) const
	Compare with input algorithm.
virtual void	SetId (const AlgId &id)
	Set algorithm ID.
virtual void	SetId (string name, string config)
const Algorithm *	SubAlg (const RgKey &registry_key) const
void	AdoptConfig (void)
void	AdoptSubstructure (void)
virtual void	Print (ostream &stream) const
	Print algorithm info.

Private Member Functions
void	LoadConfig (void)

Private Attributes
const XSecIntegratorI *	fXSecIntegrator
double	fkAlpha
double	fkGamma
double	fEta
double	fFa0
double	fMa2
double	fMv2
double	fMuP
double	fMuN

Additional Inherited Members
Static Public Member Functions inherited from genie::Algorithm
static string	BuildParamVectKey (const std::string &comm_name, unsigned int i)
static string	BuildParamVectSizeKey (const std::string &comm_name)
static string	BuildParamMatKey (const std::string &comm_name, unsigned int i, unsigned int j)
static string	BuildParamMatRowSizeKey (const std::string &comm_name)
static string	BuildParamMatColSizeKey (const std::string &comm_name)
Protected Member Functions inherited from genie::XSecAlgorithmI
	XSecAlgorithmI ()
	XSecAlgorithmI (string name)
	XSecAlgorithmI (string name, string config)
Protected Member Functions inherited from genie::Algorithm
	Algorithm ()
	Algorithm (string name)
	Algorithm (string name, string config)
void	Initialize (void)
void	DeleteConfig (void)
void	DeleteSubstructure (void)
Registry *	ExtractLocalConfig (const Registry &in) const
Registry *	ExtractLowerConfig (const Registry &in, const string &alg_key) const
	Split an incoming configuration Registry into a block valid for the sub-algo identified by alg_key.
template<class T>
bool	GetParam (const RgKey &name, T &p, bool is_top_call=true) const
template<class T>
bool	GetParamDef (const RgKey &name, T &p, const T &def) const
template<class T>
int	GetParamVect (const std::string &comm_name, std::vector< T > &v, bool is_top_call=true) const
	Handle to load vectors of parameters.
int	GetParamVectKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
template<class T>
int	GetParamMat (const std::string &comm_name, TMatrixT< T > &mat, bool is_top_call=true) const
	Handle to load matrix of parameters.
template<class T>
int	GetParamMatSym (const std::string &comm_name, TMatrixTSym< T > &mat, bool is_top_call=true) const
int	GetParamMatKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
int	AddTopRegistry (Registry *rp, bool owns=true)
	add registry with top priority, also update ownership
int	AddLowRegistry (Registry *rp, bool owns=true)
	add registry with lowest priority, also update ownership
int	MergeTopRegistry (const Registry &r)
int	AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
	Add registries with top priority, also udated Ownerships.
Protected Attributes inherited from genie::Algorithm
bool	fAllowReconfig
bool	fOwnsSubstruc
	true if it owns its substructure (sub-algs,...)
AlgId	fID
	algorithm name and configuration set
vector< Registry * >	fConfVect
vector< bool >	fOwnerships
	ownership for every registry in fConfVect
AlgStatus_t	fStatus
	algorithm execution status
AlgMap *	fOwnedSubAlgMp
	local pool for owned sub-algs (taken out of the factory pool)

Detailed Description

Differential cross section for v+N / vbar+N elastic scattering.
Is a concrete implementation of the XSecAlgorithmI interface.
.

References:\n R.E.Hendrick and L.Li, Phys.Rev.D 19:779 (1979): L.A.Ahrens et al., Phys.Rev.D 35:785 (1987)

Author: Costas Andreopoulos <c.andreopoulos \at cern.ch> University of Liverpool

Created:\n Fabruary 15, 2005

License:\n Copyright (c) 2003-2025, The GENIE Collaboration: For the full text of the license visit http://copyright.genie-mc.org

Definition at line 32 of file AhrensNCELPXSec.h.

Constructor & Destructor Documentation

◆ AhrensNCELPXSec() [1/2]

AhrensNCELPXSec::AhrensNCELPXSec ( )

Definition at line 30 of file AhrensNCELPXSec.cxx.

                                 :
XSecAlgorithmI("genie::AhrensNCELPXSec")
{
 
}

References genie::XSecAlgorithmI::XSecAlgorithmI().

◆ AhrensNCELPXSec() [2/2]

AhrensNCELPXSec::AhrensNCELPXSec ( string config )

Definition at line 36 of file AhrensNCELPXSec.cxx.

                                              :
XSecAlgorithmI("genie::AhrensNCELPXSec", config)
{
 
}

References genie::XSecAlgorithmI::XSecAlgorithmI().

◆ ~AhrensNCELPXSec()

AhrensNCELPXSec::~AhrensNCELPXSec ( )

virtual

Definition at line 42 of file AhrensNCELPXSec.cxx.

{
 
}

Member Function Documentation

◆ Configure() [1/2]

void AhrensNCELPXSec::Configure ( const Registry & config )

virtual

Configure the algorithm with an external registry The registry is merged with the top level registry if it is owned, Otherwise a copy of it is added with the highest priority

Reimplemented from genie::Algorithm.

Definition at line 142 of file AhrensNCELPXSec.cxx.

{
  Algorithm::Configure(config);
  this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

◆ Configure() [2/2]

void AhrensNCELPXSec::Configure ( string config )

virtual

Configure the algorithm from the AlgoConfigPool based on param_set string given in input An algorithm contains a vector of registries coming from different xml configuration files, which are loaded according a very precise prioriy This methods will load a number registries in order of priority: 1) "Tunable" parameter set from CommonParametes. This is loaded with the highest prioriry and it is designed to be used for tuning procedure Usage not expected from the user. 2) For every string defined in "CommonParame" the corresponding parameter set will be loaded from CommonParameter.xml 3) parameter set specified by the config string and defined in the xml file of the algorithm 4) if config is not "Default" also the Default parameter set from the same xml file will be loaded Effectively this avoids the repetion of a parameter when it is not changed in the requested configuration

Reimplemented from genie::Algorithm.

Definition at line 148 of file AhrensNCELPXSec.cxx.

{
  Algorithm::Configure(config);
  this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

◆ Integral()

double AhrensNCELPXSec::Integral ( const Interaction * i ) const

virtual

Integrate the model over the kinematic phase space available to the input interaction (kinematical cuts can be included)

Implements genie::XSecAlgorithmI.

Definition at line 130 of file AhrensNCELPXSec.cxx.

{
  double xsec = fXSecIntegrator->Integrate(this,interaction);
  return xsec;
}

References fXSecIntegrator.

◆ LoadConfig()

void AhrensNCELPXSec::LoadConfig ( void )

private

Definition at line 154 of file AhrensNCELPXSec.cxx.

{
  // alpha and gamma
  double thw ;
  GetParam( "WeinbergAngle", thw ) ;
  double sin2thw = TMath::Power(TMath::Sin(thw), 2);
  fkAlpha = 1.-2.*sin2thw;
  fkGamma = -0.66666667*sin2thw;
 
  // eta and Fa(q2=0)
  GetParam( "EL-Axial-Eta", fEta ) ;
  GetParam( "QEL-FA0", fFa0 ) ;
 
  // axial and vector masses
  double ma, mv ;
  GetParam( "QEL-Ma", ma ) ;
  GetParam( "QEL-Mv", mv ) ;
  fMa2 = TMath::Power(ma,2);
  fMv2 = TMath::Power(mv,2);
 
  // anomalous magnetic moments
  GetParam( "AnomMagnMoment-P", fMuP ) ;
  GetParam( "AnomMagnMoment-N", fMuN ) ;
 
  // load XSec Integrator
  fXSecIntegrator =
      dynamic_cast<const XSecIntegratorI *> (this->SubAlg("XSec-Integrator"));
  assert(fXSecIntegrator);
}

References fEta, fFa0, fkAlpha, fkGamma, fMa2, fMuN, fMuP, fMv2, fXSecIntegrator, genie::Algorithm::GetParam(), and genie::Algorithm::SubAlg().

Referenced by Configure(), and Configure().

◆ ValidProcess()

bool AhrensNCELPXSec::ValidProcess ( const Interaction * i ) const

virtual

Can this cross section algorithm handle the input process?

Implements genie::XSecAlgorithmI.

Definition at line 136 of file AhrensNCELPXSec.cxx.

{
  if(interaction->TestBit(kISkipProcessChk)) return true;
  return true;
}

References genie::kISkipProcessChk.

Referenced by XSec().

◆ XSec()

double AhrensNCELPXSec::XSec	(	const Interaction *	i,
		KinePhaseSpace_t	k ) const

virtual

Compute the cross section for the input interaction.

Implements genie::XSecAlgorithmI.

Definition at line 47 of file AhrensNCELPXSec.cxx.

{
  if(! this -> ValidProcess    (interaction) ) return 0.;
  if(! this -> ValidKinematics (interaction) ) return 0.;
 
  const InitialState & init_state = interaction -> InitState();
  const Kinematics &   kinematics = interaction -> Kine();
  const Target &       target     = init_state.Tgt();
 
  double E    = init_state.ProbeE(kRfHitNucRest);
  double Q2   = kinematics.Q2();
  double M    = target.HitNucMass();
  double M2   = TMath::Power(M, 2.);
  double E2   = TMath::Power(E, 2.);
  double qmv2 = TMath::Power(1 + Q2/fMv2, 2);
  double qma2 = TMath::Power(1 + Q2/fMa2, 2);
 
  //-- handle terms changing sign for antineutrinos and isospin rotations
  int nusign  = 1;
  int nucsign = 1;
  int nupdgc  = init_state.ProbePdg();
  int nucpdgc = target.HitNucPdg();
  if( pdg::IsAntiNeutrino(nupdgc) ) nusign  = -1;
  if( pdg::IsNeutron(nucpdgc)     ) nucsign = -1;
 
  //-- compute isoscalar form factor terms
  double Ge0 = 1.5 * fkGamma / qmv2;
  double Gm0 = 1.5 * fkGamma * (fMuP+fMuN) / qmv2;
 
  //-- compute isovector form factor terms
  double Ge1 = 0.5 * fkAlpha / qmv2;
  double Gm1 = 0.5 * fkAlpha * (fMuP-fMuN) / qmv2;
  double Ga1 = -0.5 * fFa0 * (1 + (nucsign) * fEta) / qma2;
 
  //-- compute form factors
  double Ge  = Ge0 + (nucsign) * Ge1;
  double Gm  = Gm0 + (nucsign) * Gm1;
  double Ga  = (nucsign) * Ga1;
  double Ge2 = TMath::Power(Ge,2);
  double Gm2 = TMath::Power(Gm,2);
  double Ga2 = TMath::Power(Ga,2);
 
  //-- compute the free nucleon cross section
  double tau   = 0.25 * Q2/M2;
  double fa    = 1-M*tau/E;
  double fa2   = TMath::Power(fa,2);
  double fb    = tau*(tau+1)*M2/E2;
  double A     = (Ge2/(1+tau))           * (fa2-fb);
  double B     = (Ga2 + tau*Gm2/(1+tau)) * (fa2+fb);
  double C     = 4*tau*(M/E)*Gm*Ga       * fa;
  double xsec0 = 0.5*kGF2/kPi;
  double xsec  = xsec0 * (A + B + (nusign)*C);
 
  LOG("AhrensNCEL", pDEBUG)
    << "dXSec[vN,El]/dQ2 [FreeN](Ev = "<< E<< ", Q2 = "<< Q2 << ") = "<< xsec;
 
  //-- The algorithm computes dxsec/dQ2
  //   Check whether variable tranformation is needed
  if(kps!=kPSQ2fE) {
    double J = utils::kinematics::Jacobian(interaction,kPSQ2fE,kps);
    xsec *= J;
  }
 
  //-- if requested return the free nucleon xsec even for input nuclear tgt
  if( interaction->TestBit(kIAssumeFreeNucleon) ) return xsec;
 
  //-- compute nuclear suppression factor
  //   (R(Q2) is adapted from NeuGEN - see comments therein)
  double R = nuclear::NuclQELXSecSuppression("Default", 0.5, interaction);
 
  //-- number of scattering centers in the target
  int NNucl = (pdg::IsProton(nucpdgc)) ? target.Z() : target.N();
 
  LOG("AhrensNCEL", pDEBUG)
       << "Nuclear suppression factor R(Q2) = " << R << ", NNucl = " << NNucl;
 
  //-- compute nuclear cross section
  xsec *= (R*NNucl);
 
  return xsec;
}

References fEta, fFa0, fkAlpha, fkGamma, fMa2, fMuN, fMuP, fMv2, genie::Target::HitNucMass(), genie::Target::HitNucPdg(), genie::pdg::IsAntiNeutrino(), genie::pdg::IsNeutron(), genie::pdg::IsProton(), genie::utils::kinematics::Jacobian(), genie::constants::kGF2, genie::kIAssumeFreeNucleon, genie::constants::kPi, genie::kPSQ2fE, genie::kRfHitNucRest, LOG, genie::Target::N(), genie::utils::nuclear::NuclQELXSecSuppression(), pDEBUG, genie::InitialState::ProbeE(), genie::InitialState::ProbePdg(), genie::InitialState::Tgt(), genie::XSecAlgorithmI::ValidKinematics(), ValidProcess(), and genie::Target::Z().

Member Data Documentation

◆ fEta

double genie::AhrensNCELPXSec::fEta

private

Definition at line 56 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fFa0

double genie::AhrensNCELPXSec::fFa0

private

Definition at line 57 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fkAlpha

double genie::AhrensNCELPXSec::fkAlpha

private

Definition at line 54 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fkGamma

double genie::AhrensNCELPXSec::fkGamma

private

Definition at line 55 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fMa2

double genie::AhrensNCELPXSec::fMa2

private

Definition at line 58 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fMuN

double genie::AhrensNCELPXSec::fMuN

private

Definition at line 61 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fMuP

double genie::AhrensNCELPXSec::fMuP

private

Definition at line 60 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fMv2

double genie::AhrensNCELPXSec::fMv2

private

Definition at line 59 of file AhrensNCELPXSec.h.

Referenced by LoadConfig(), and XSec().

◆ fXSecIntegrator

const XSecIntegratorI* genie::AhrensNCELPXSec::fXSecIntegrator

private

Definition at line 52 of file AhrensNCELPXSec.h.

Referenced by Integral(), and LoadConfig().

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

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ AhrensNCELPXSec() [1/2]

◆ AhrensNCELPXSec() [2/2]

◆ ~AhrensNCELPXSec()

Member Function Documentation

◆ Configure() [1/2]

◆ Configure() [2/2]

◆ Integral()

◆ LoadConfig()

◆ ValidProcess()

◆ XSec()

Member Data Documentation

◆ fEta

◆ fFa0

◆ fkAlpha

◆ fkGamma

◆ fMa2

◆ fMuN

◆ fMuP

◆ fMv2

◆ fXSecIntegrator