InitialStateAppender.cxx

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//____________________________________________________________________________
/*
 Copyright (c) 2003-2025, The GENIE Collaboration
 For the full text of the license visit http://copyright.genie-mc.org
 
 Costas Andreopoulos <c.andreopoulos \at cern.ch>
 University of Liverpool 
*/
//____________________________________________________________________________
 
#include <TLorentzVector.h>
 
#include "Physics/Common/InitialStateAppender.h"
#include "Framework/GHEP/GHepStatus.h"
#include "Framework/GHEP/GHepParticle.h"
#include "Framework/GHEP/GHepRecord.h"
#include "Framework/Interaction/Interaction.h"
#include "Framework/Messenger/Messenger.h"
#include "Framework/ParticleData/PDGLibrary.h"
#include "Framework/ParticleData/PDGCodes.h"
#include "Framework/ParticleData/PDGUtils.h"
 
using namespace genie;
 
//___________________________________________________________________________
InitialStateAppender::InitialStateAppender() :
EventRecordVisitorI("genie::InitialStateAppender")
{
 
}
//___________________________________________________________________________
InitialStateAppender::InitialStateAppender(string config) :
EventRecordVisitorI("genie::InitialStateAppender", config)
{
 
}
//___________________________________________________________________________
InitialStateAppender::~InitialStateAppender()
{
 
}
//___________________________________________________________________________
void InitialStateAppender::ProcessEventRecord(GHepRecord * evrec) const
{
// Adds the initial state particles at the event record (the order is
// significant)
 
  LOG("ISApp", pINFO) << "Adding the initial state to the event record";
 
  //-- add the incoming neutrino to the event record
  this->AddNeutrino(evrec);
 
  //-- add the nuclear target at the event record (if any)
  this->AddNucleus(evrec);
 
  //-- add the struck nucleon to the event record (if any)
  //   It is added with status-code = 0 (init state) if the target was a
  //   free nucleon, or with a status-code = 11 (nucleon target) if the
  //   target was a nucleus.
  //   If the interaction was ve- elastic, inverse muon decay or Glashow
  //   resonance then it will add the target e- instead.
  this->AddStruckParticle(evrec);
  LOG("ISApp", pINFO) << *evrec;
}
//___________________________________________________________________________
void InitialStateAppender::AddNeutrino(GHepRecord * evrec) const
{
  Interaction * interaction = evrec->Summary();
  const InitialState & init_state = interaction->InitState();
 
  TLorentzVector * p4 = init_state.GetProbeP4(kRfLab);
  const TLorentzVector v4(0.,0.,0.,0.);
 
  int pdgc = init_state.ProbePdg();
 
  LOG("ISApp", pINFO) << "Adding neutrino [pdgc = " << pdgc << "]";
 
  evrec->AddParticle(pdgc,kIStInitialState, -1,-1,-1,-1, *p4, v4);
 
  delete p4;
}
//___________________________________________________________________________
void InitialStateAppender::AddNucleus(GHepRecord * evrec) const
{
  Interaction * interaction = evrec->Summary();
  const InitialState & init_state = interaction->InitState();
  const ProcessInfo & proc_info   = interaction->ProcInfo();
 
  bool is_nucleus = init_state.Tgt().IsNucleus() || proc_info.IsNorm();
  if(!is_nucleus && !proc_info.IsGlashowResonance() && !proc_info.IsPhotonCoherent()) {
    LOG("ISApp", pINFO)
         << "Not an interaction with a nuclear target - no nucleus to add";
    return;
  }
  int    A    = init_state.Tgt().A();
  int    Z    = init_state.Tgt().Z();
  int    pdgc = pdg::IonPdgCode(A, Z);
  double M    = PDGLibrary::Instance()->Find(pdgc)->Mass();
 
  LOG("ISApp", pINFO)
          << "Adding nucleus [A = " << A << ", Z = " << Z
                                              << ", pdg = " << pdgc << "]";
 
  evrec->AddParticle(pdgc,kIStInitialState,-1,-1,-1,-1, 0,0,0,M, 0,0,0,0);
}
//___________________________________________________________________________
void InitialStateAppender::AddStruckParticle(GHepRecord * evrec) const
{
  Interaction * interaction = evrec->Summary();
  const InitialState & init_state = interaction->InitState();
  const ProcessInfo & proc_info   = interaction->ProcInfo();
 
  // EDIT: Add the dark matter scattering off electron here
  bool hit_e = proc_info.IsInverseMuDecay()    ||
               proc_info.IsIMDAnnihilation()   ||
               proc_info.IsNuElectronElastic() ||
               proc_info.IsDarkMatterElectronElastic() ||
               proc_info.IsGlashowResonance();
 
  if(hit_e) {
    int    pdgc = kPdgElectron;
    double mass = PDGLibrary::Instance()->Find(pdgc)->Mass();
    const TLorentzVector p4(0,0,0, mass);
    const TLorentzVector v4(0.,0.,0.,0.);
 
    LOG("ISApp", pINFO) << "Adding struck electron";
    evrec->AddParticle(pdgc, kIStInitialState, 1, -1, -1, -1, p4, v4);
    return;
  }
 
  int pdgc = init_state.Tgt().HitNucPdg();
 
  if(pdgc != 0) {
 
    bool is_nucleus = init_state.Tgt().IsNucleus();
 
    GHepStatus_t ist   = (is_nucleus) ? kIStNucleonTarget : kIStInitialState;
    int          imom1 = (is_nucleus) ? 1 : -1;
    int          imom2 = -1;
 
    const TLorentzVector p4(init_state.Tgt().HitNucP4());
    const TLorentzVector v4(0.,0.,0.,0.);
 
    LOG("ISApp", pINFO)<< "Adding struck nucleon [pdgc = " << pdgc << "]";
 
    evrec->AddParticle(pdgc, ist, imom1, imom2, -1, -1, p4, v4);
 
  }//if struck nucleon was set
}
//___________________________________________________________________________