decayactiondilepton.h

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/*
 *
 *    Copyright (c) 2015-2022
 *      SMASH Team
 *
 *    GNU General Public License (GPLv3 or later)
 *
 */
 
#ifndef SRC_INCLUDE_SMASH_DECAYACTIONDILEPTON_H_
#define SRC_INCLUDE_SMASH_DECAYACTIONDILEPTON_H_
 
#include "decayaction.h"
 
namespace smash {
 
/**
 * \ingroup action
 * DecayActionDilepton is special action created for particles
 * that can decay into dileptons. Such actions are never actually
 * performed, but only written into the dilepton output according to
 * our perturbative treatment.
 */
class DecayActionDilepton : public DecayAction {
 public:
  /**
   * Construct a DecayActionDilepton from a particle \p p.
   *
   * It does not initialize the list of possible decay processes. You need to
   * call add_processes after construction.
   *
   * \param[in] p The particle that should decay if the action is performed.
   * \param[in] time_of_execution Time at which the action is supposed to take
   *                              place
   * \param[in] shining_weight The weight of the dilepton decay accroding
   *                           to the shining method.
   */
  DecayActionDilepton(const ParticleData &p, double time_of_execution,
                      double shining_weight);
 
  double get_total_weight() const override {
    return shining_weight_ * branching_;
  }
 
  /**
   * Generates momenta of outgoing dileptons (for Dalitz dilepton decays only).
   */
  void sample_manybody_phasespace() override;
 
 private:
  /**
   * The shining weight is a weight you apply to every dilepton decay. Because
   * we radiate dileptons at every timestep to increase statistics, we
   * afterwards weight them to correct the dilepton decay yields.
   */
  const double shining_weight_;
  /**
   * An additional branching factor that is multiplied with the shining weight.
   * For Dalitz decays, the primary shining weight is based on the integrated
   * width for the channel, and the branching factor corrects for the
   * differential width (evaluated at a particular dilepton mass), relative
   * to the integrated width. It is determined after the dilepton mass is fixed.
   * For direct (2-body) decays, the branching factor equals one.
   */
  double branching_ = 1.;
};
 
}  // namespace smash
 
#endif  // SRC_INCLUDE_SMASH_DECAYACTIONDILEPTON_H_