MECGenerator.h

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//____________________________________________________________________________
/*!

\class    genie::MECGenerator

\brief    Simulate the primary MEC interaction

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

          Steve Dytman <dytman+ \at pitt.edu>
          Pittsburgh University

\created  Sep. 22, 2008

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

#ifndef _MEC_GENERATOR_H_
#define _MEC_GENERATOR_H_

#include <TGenPhaseSpace.h>
#include "Framework/Utils/Range1.h"

#include "Framework/EventGen/EventRecordVisitorI.h"
#include "Framework/ParticleData/PDGCodeList.h"

namespace genie {

class Interaction;
class NuclearModelI;
class XSecAlgorithmI;

class MECGenerator : public EventRecordVisitorI {

public :
  MECGenerator();
  MECGenerator(string config);
 ~MECGenerator();

  // implement the EventRecordVisitorI interface
  void ProcessEventRecord (GHepRecord * event) 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);
  void    AddNucleonCluster                 (GHepRecord * event) const;
  void    AddTargetRemnant                  (GHepRecord * event) const;
  void    GenerateFermiMomentum             (GHepRecord * event) const;
  void    SelectEmpiricalKinematics         (GHepRecord * event) const;
  void    AddFinalStateLepton               (GHepRecord * event) const;
  void    RecoilNucleonCluster              (GHepRecord * event) const;
  void    DecayNucleonCluster               (GHepRecord * event) const;
  void    SelectNSVLeptonKinematics         (GHepRecord * event) const;
  void    SelectSuSALeptonKinematics        (GHepRecord * event) const;
  void    GenerateNSVInitialHadrons         (GHepRecord * event) const;
  PDGCodeList NucleonClusterConstituents    (int pdgc)           const;

  // Helper function that computes the maximum differential cross section
  // in the kPSTlctl phase space
  double GetXSecMaxTlctl( const Interaction & inter, const Range1D_t & Tl_range, const Range1D_t & ctl_range ) const;

  mutable const XSecAlgorithmI * fXSecModel;
  mutable TGenPhaseSpace         fPhaseSpaceGenerator;
  const NuclearModelI *          fNuclModel;

  double fSafetyFactor ; 
  int fFunctionCalls ; 
  double fRelTolerance ; // Relative tolerance 
  int fMinScanPointsTmu ; 
  int fMinScanPointsCosth ; 
  
  double fQ3Max;

  // Tolerate this maximum percent deviation above the calculated maximum cross
  // section when sampling lepton kinematics for the SuSAv2-MEC model.
  double fSuSAMaxXSecDiffTolerance;
};

}      // genie namespace
#endif // _MEC_GENERATOR_H_