scatteraction.h

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/*
 *
 *    Copyright (c) 2015-2018
 *      SMASH Team
 *
 *    GNU General Public License (GPLv3 or later)
 *
 */

#ifndef SRC_INCLUDE_SCATTERACTION_H_
#define SRC_INCLUDE_SCATTERACTION_H_

#include <memory>
#include <set>
#include <string>
#include <utility>

#include "action.h"
#include "cxx14compat.h"
#include "isoparticletype.h"
#include "kinematics.h"
#include "processstring.h"

namespace smash {

class ScatterAction : public Action {
 public:
  ScatterAction(const ParticleData& in_part1, const ParticleData& in_part2,
                double time, bool isotropic = false,
                double string_formation_time = 1.0);

  void add_collision(CollisionBranchPtr p);

  void add_collisions(CollisionBranchList pv);

  double transverse_distance_sqr() const;

  void generate_final_state() override;

  double get_total_weight() const override;

  double get_partial_weight() const override;

  void sample_angles(std::pair<double, double> masses,
                     double kinetic_energy_cm) override;

  void add_all_scatterings(double elastic_parameter, bool two_to_one,
                           ReactionsBitSet included_2to2, double low_snn_cut,
                           bool strings_switch, bool use_AQM,
                           bool strings_with_probability,
                           NNbarTreatment nnbar_treatment);

  const CollisionBranchList& collision_channels() {
    return collision_channels_;
  }

  class InvalidScatterAction : public std::invalid_argument {
    using std::invalid_argument::invalid_argument;
  };

  void set_string_interface(StringProcess* str_proc) {
    string_process_ = str_proc;
  }

  virtual double cross_section() const { return total_cross_section_; }

 protected:
  double mandelstam_s() const;
  double cm_momentum() const;
  double cm_momentum_squared() const;
  ThreeVector beta_cm() const;
  double gamma_cm() const;

  void elastic_scattering();

  void inelastic_scattering();

  void string_excitation();

  void format_debug_output(std::ostream& out) const override;

  CollisionBranchList collision_channels_;

  double total_cross_section_;

  double partial_cross_section_;

  bool isotropic_ = false;

  double string_formation_time_ = 1.0;

 private:
  bool is_elastic() const;

  void resonance_formation();

  StringProcess* string_process_ = nullptr;
};

}  // namespace smash

#endif  // SRC_INCLUDE_SCATTERACTION_H_