marley::NucleonFormFactors Class Reference

Calculates nucleon form factors for both vector and axial currents. More...

#include <NucleonFormFactors.hh>

Public Member Functions
	NucleonFormFactors (const JSON &config)
const AxialFormFactors *	axial_ff () const
	Get const access to the owned axial form factors.
double	F1 (double Q2) const
double	F1n (double Q2) const
double	F1p (double Q2) const
double	F2 (double Q2) const
double	F2n (double Q2) const
double	F2p (double Q2) const
double	FA (double Q2) const
double	FP (double Q2) const
const SachsFormFactors *	sachs_ff () const
	Get const access to the owned Sachs form factors.

Protected Attributes
std::shared_ptr< AxialFormFactors >	axial_ff_
std::shared_ptr< SachsFormFactors >	sachs_ff_

Detailed Description

Calculates nucleon form factors for both vector and axial currents.

Definition at line 150 of file NucleonFormFactors.hh.

Constructor & Destructor Documentation

NucleonFormFactors()

marley::NucleonFormFactors::NucleonFormFactors

(

const JSON &

config

)

Definition at line 140 of file NucleonFormFactors.cc.

                                                                       {
 
  // Flag used to ensure that we send information about the form factor
  // configuration to the logger exactly once when this function is first
  // called
  static bool need_to_log = true;
 
  // If the user has requested use of the allowed approximation, then
  // configure trivial form factor models and return without logging this
  // choice (it will be handled elsewhere)
  if ( marley::JSONConfig::check_for_allowed_approximation(config) ) {
    sachs_ff_ = std::make_shared< TrivialSachsFormFactors >();
    axial_ff_ = std::make_shared< TrivialAxialFormFactors >();
    need_to_log = false;
    return;
  }
 
  if ( !config.has_key("sachs_model") ) {
    throw marley::Error( "Missing Sachs form factor model configuration" );
  }
  const auto& sachs_json = config.at( "sachs_model" );
  if ( !sachs_json.is_string() ) {
    throw marley::Error( "Invalid Sachs form factor model "
      + sachs_json.dump_string() );
  }
  std::string sachs_ff_model = sachs_json.to_string();
 
  if ( !config.has_key("axial_model") ) {
    throw marley::Error( "Missing axial form factor model configuration" );
  }
  const auto& axial_json = config.at( "axial_model" );
  if ( !axial_json.is_string() ) {
    throw marley::Error( "Invalid axial form factor model "
      + axial_json.dump_string() );
  }
  std::string axial_ff_model = axial_json.to_string();
 
  // Choose the model to use for the Sachs form factors
  if ( sachs_ff_model == "trivial" ) {
    sachs_ff_ = std::make_shared< TrivialSachsFormFactors >();
    if ( need_to_log ) {
      MARLEY_LOG( INFO, "physics.formfactor" ) << "Using trivial Sachs form factors";
    }
  }
  else if ( sachs_ff_model == "dipole" ) {
    sachs_ff_ = std::make_shared< DipoleSachsFormFactors >( marley_utils::M_V );
    if ( need_to_log ) {
      MARLEY_LOG( INFO, "physics.formfactor" ) << "Using dipole Sachs form factors";
    }
  }
  else if ( sachs_ff_model == "bbba05" ) {
    sachs_ff_ = std::make_shared< BBBA05SachsFormFactors >();
    if ( need_to_log ) {
      MARLEY_LOG( INFO, "physics.formfactor" ) << "Using BBBA05 Sachs form factors";
    }
  }
  else throw marley::Error( "Unrecognized Sachs form factor model name \""
    + sachs_ff_model + "\" in constructor of marley::NucleonFormFactors" );
 
  // Choose the model to use for the axial form factors
  if ( axial_ff_model == "trivial" ) {
    axial_ff_ = std::make_shared< TrivialAxialFormFactors >();
    if ( need_to_log ) {
      MARLEY_LOG( INFO, "physics.formfactor" ) << "Using trivial axial form factors";
    }
  }
  else if ( axial_ff_model == "dipole" ) {
    axial_ff_ = std::make_shared< DipoleAxialFormFactors >( marley_utils::g_A,
      marley_utils::M_A );
    if ( need_to_log ) {
      MARLEY_LOG( INFO, "physics.formfactor" ) << "Using dipole axial form factors";
    }
  }
  else throw marley::Error( "Unrecognized axial form factor model name \""
    + axial_ff_model + "\" in constructor of marley::NucleonFormFactors" );
 
  need_to_log = false;
}

Member Function Documentation

axial_ff()

const AxialFormFactors * marley::NucleonFormFactors::axial_ff ( ) const

inline

Get const access to the owned axial form factors.

Definition at line 202 of file NucleonFormFactors.hh.

        { return axial_ff_.get(); }

F1()

double marley::NucleonFormFactors::F1 ( double Q2 ) const

inline

Charged-current vector form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 158 of file NucleonFormFactors.hh.

        { return this->F1p( Q2 ) - this->F1n( Q2 ); }

References F1n(), and F1p().

F1n()

double marley::NucleonFormFactors::F1n

(

double

Q2

)

const

Neutron vector form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 116 of file NucleonFormFactors.cc.

                                                      {
  double tau = sachs_ff_->tau( Q2 );
  double GEn = sachs_ff_->GEn( Q2 );
  double GMn = sachs_ff_->GMn( Q2 );
  double F1n = ( GEn + tau*GMn ) / ( 1. + tau );
  return F1n;
}

References F1n().

Referenced by F1(), and F1n().

F1p()

double marley::NucleonFormFactors::F1p

(

double

Q2

)

const

Proton vector form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 108 of file NucleonFormFactors.cc.

                                                      {
  double tau = sachs_ff_->tau( Q2 );
  double GEp = sachs_ff_->GEp( Q2 );
  double GMp = sachs_ff_->GMp( Q2 );
  double F1p = ( GEp + tau*GMp ) / ( 1. + tau );
  return F1p;
}

References F1p().

Referenced by F1(), and F1p().

F2()

double marley::NucleonFormFactors::F2 ( double Q2 ) const

inline

Charged-current weak magnetic form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 164 of file NucleonFormFactors.hh.

        { return this->F2p( Q2 ) - this->F2n( Q2 ); }

References F2n(), and F2p().

F2n()

double marley::NucleonFormFactors::F2n

(

double

Q2

)

const

Neutron weak magnetic form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 132 of file NucleonFormFactors.cc.

                                                      {
  double tau = sachs_ff_->tau( Q2 );
  double GEn = sachs_ff_->GEn( Q2 );
  double GMn = sachs_ff_->GMn( Q2 );
  double F2n = ( GMn - GEn ) / ( 1. + tau ) / 2. / marley_utils::m_nucleon;
  return F2n;
}

References F2n().

Referenced by F2(), and F2n().

F2p()

double marley::NucleonFormFactors::F2p

(

double

Q2

)

const

Proton weak magnetic form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 124 of file NucleonFormFactors.cc.

                                                      {
  double tau = sachs_ff_->tau( Q2 );
  double GEp = sachs_ff_->GEp( Q2 );
  double GMp = sachs_ff_->GMp( Q2 );
  double F2p = ( GMp - GEp ) / ( 1. + tau ) / 2. / marley_utils::m_nucleon;
  return F2p;
}

References F2p().

Referenced by F2(), and F2p().

FA()

double marley::NucleonFormFactors::FA ( double Q2 ) const

inline

Charged-current axial-vector form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 190 of file NucleonFormFactors.hh.

{ return axial_ff_->FA( Q2 ); }

FP()

double marley::NucleonFormFactors::FP ( double Q2 ) const

inline

Charged-current pseudoscalar form factor

Parameters

Q2	Negative square \( Q^{2} \) of the four-momentum transfer (MeV 2)

Definition at line 195 of file NucleonFormFactors.hh.

{ return axial_ff_->FP( Q2 ); }

sachs_ff()

const SachsFormFactors * marley::NucleonFormFactors::sachs_ff ( ) const

inline

Get const access to the owned Sachs form factors.

Definition at line 198 of file NucleonFormFactors.hh.

        { return sachs_ff_.get(); }

Member Data Documentation

axial_ff_

std::shared_ptr< AxialFormFactors > marley::NucleonFormFactors::axial_ff_

protected

Definition at line 208 of file NucleonFormFactors.hh.

sachs_ff_

std::shared_ptr< SachsFormFactors > marley::NucleonFormFactors::sachs_ff_

protected

Definition at line 207 of file NucleonFormFactors.hh.

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

• /home/sjg/Desktop/marley/include/marley/NucleonFormFactors.hh
• /home/sjg/Desktop/marley/src/NucleonFormFactors.cc