ReinSehgalCOHPiPXSec.h

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//____________________________________________________________________________
/*!

\class    genie::ReinSehgalCOHPiPXSec

\brief    Computes the double differential cross section for CC & NC coherent
          pion production according to the \b Rein-Sehgal model.
          v(vbar)A->v(vbar)Api0, vA->l-Api+, vbarA->l+Api-

          The t-dependence of the triple differential cross (d^3xsec/dxdydt)
          is analytically integrated out.

          Is a concrete implementation of the XSecAlgorithmI interface.

\ref      D.Rein and L.M.Sehgal, Coherent pi0 production in neutrino
          reactions, Nucl.Phys.B223:29-144 (1983)

          D.Rein and L.M.Sehgal, PCAC and the Deficit of Forward Muons in pi+
          Production by Neutrinos, hep-ph/0606185

\author   Costas Andreopoulos <constantinos.andreopoulos \at cern.ch>
          University of Liverpool & STFC Rutherford Appleton Laboratory

\created  March 11, 2005

\cpright  Copyright (c) 2003-2020, The GENIE Collaboration
          For the full text of the license visit http://copyright.genie-mc.org          
*/
//____________________________________________________________________________

#ifndef _REIN_SEHGAL_COHPI_PXSEC_H_
#define _REIN_SEHGAL_COHPI_PXSEC_H_

#include "Framework/EventGen/XSecAlgorithmI.h"

namespace genie {

class XSecIntegratorI;

class ReinSehgalCOHPiPXSec : public XSecAlgorithmI {

public:
  ReinSehgalCOHPiPXSec();
  ReinSehgalCOHPiPXSec(string config);
  virtual ~ReinSehgalCOHPiPXSec();

  //-- XSecAlgorithmI interface implementation
  double XSec            (const Interaction * i, KinePhaseSpace_t k) const;
  double Integral        (const Interaction * i) const;
  bool   ValidProcess    (const Interaction * i) const;

  //-- overload the Algorithm::Configure() methods to load private data
  //   members from configuration options
  void Configure(const Registry & config);
  void Configure(string config);

private:
  void LoadConfig(void);

  //-- private data members loaded from config Registry or set to defaults
  double fMa;      ///< axial mass
  double fReIm;    ///< Re/Im {forward pion scattering amplitude}
  double fRo;      ///< nuclear size scale parameter
  bool   fModPCAC; ///< use modified PCAC (including f/s lepton mass)

  const XSecIntegratorI * fXSecIntegrator;
};

}       // genie namespace

#endif  // _REIN_SEHGAL_COHPI_PXSEC_H_