Parameterisation.h

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/*
 *  CepGen: a central exclusive processes event generator
 *  Copyright (C) 2013-2024  Laurent Forthomme
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef CepGen_FormFactors_Parameterisation_h
#define CepGen_FormFactors_Parameterisation_h
 
#include "CepGen/FormFactors/FormFactors.h"
#include "CepGen/Modules/NamedModule.h"
#include "CepGen/Physics/HeavyIon.h"
 
namespace cepgen {
  namespace formfac {
    class Parameterisation : public NamedModule<Parameterisation> {
    public:
      explicit Parameterisation(const ParametersList&);
 
      static ParametersDescription description();
 
      friend std::ostream& operator<<(std::ostream&, const Parameterisation&);  
 
      double tau(double q2) const;  
 
      virtual const FormFactors& operator()(double /*q2*/);  
      virtual bool fragmenting() const { return false; }     
 
    protected:
      static constexpr double MU = 2.792847337;  
 
      virtual void eval() = 0;  
 
      void setFEFM(double fe, double fm);  
      void setGEGM(double ge, double gm);  
 
      const pdgid_t pdg_id_;  
      const double mass2_;    
      const double mp_;       
      const double mp2_;      
 
      double q2_{-1.};    
      FormFactors ff_{};  
    };
    std::ostream& operator<<(std::ostream&, const FormFactors&);
  }  // namespace formfac
}  // namespace cepgen
 
#endif