TEvtGenDecayer.h

Go to the documentation of this file.

// SPDX-License-Identifier: LGPL-3.0-or-later
// SPDX-FileCopyrightText: Copyright CERN for the benefit of the SHiP
// Collaboration
 
#ifndef SHIPGEN_TEVTGENDECAYER_H_
#define SHIPGEN_TEVTGENDECAYER_H_
 
// Custom external decayer that uses EvtGen for specific particles (like J/psi)
// and falls back to TPythia8Decayer for others
 
#include <vector>
 
#include "TPythia8Decayer.h"
#include "TString.h"
#include "TVirtualMCDecayer.h"
 
class TClonesArray;
class TLorentzVector;
class EvtGen;
class EvtParticle;
 
class TEvtGenDecayer : public TVirtualMCDecayer {
 public:
  TEvtGenDecayer();
  ~TEvtGenDecayer() override;
 
  void Init() override;
  void Decay(Int_t pdg, TLorentzVector* p) override;
  Int_t ImportParticles(TClonesArray* particles) override;
  void SetForceDecay(Int_t type) override;
  void ForceDecay() override;
  Float_t GetPartialBranchingRatio(Int_t ipart) override;
  Float_t GetLifetime(Int_t kf) override;
  void ReadDecayTable() override;
 
  // EvtGen-specific methods
  void SetEvtGenDecayFile(const char* decayFile);
  void SetEvtGenParticleFile(const char* particleFile);
  void AddEvtGenParticle(Int_t pdg);  // Add particle to be handled by EvtGen
 
  // Access methods
  TPythia8Decayer* GetPythia8Decayer() { return fPythia8Decayer; }
 
 protected:
  Bool_t UseEvtGenForParticle(Int_t pdg);
  void DecayWithEvtGen(Int_t pdg, TLorentzVector* p);
  void DecayWithPythia8(Int_t pdg, TLorentzVector* p);
  void ConvertEvtGenDecay(EvtParticle* parent);
 
 private:
  TPythia8Decayer*
      fPythia8Decayer;    // Fallback decayer for non-EvtGen particles
  EvtGen* fEvtGen;        // EvtGen instance
  TString fDecayFile;     // EvtGen DECAY.DEC file
  TString fParticleFile;  // EvtGen particle data file
  std::vector<Int_t>
      fEvtGenParticles;  // List of PDG codes to handle with EvtGen
 
  // Storage for EvtGen decay products
  TClonesArray* fEvtGenProducts;  // Array to store converted EvtGen particles
  Bool_t fHasEvtGenDecay;  // Flag indicating if last decay was from EvtGen
};
 
#endif  // SHIPGEN_TEVTGENDECAYER_H_