EvtGenDecayModule.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
/* External headers. */
#include <EvtGenBase/EvtPDL.hh>
#include <EvtGenBase/EvtDecayTable.hh>
 
/* Belle 2 headers. */
#include <framework/datastore/StoreArray.h>
#include <framework/utilities/FileSystem.h>
#include <generators/modules/evtgendecay/EvtGenDecayModule.h>
 
using namespace Belle2;
 
REG_MODULE(EvtGenDecay)
 
EvtGenDecayModule::EvtGenDecayModule() : Module()
{
  setDescription("This module decays unstable particles using EvtGen. The "
                 "event should be already generated by another generator. "
                 "If you need to generate full event with EvtGen, then use "
                 "the module 'EvtGenInput'.");
  addParam("DecFile", m_DecFile, "EvtGen decay file (DECAY.DEC)",
           FileSystem::findFile(
             "decfiles/dec/DECAY_BELLE2.DEC", true));
  addParam("UserDecFile", m_UserDecFile, "User EvtGen decay file",
           std::string(""));
  addParam("MCParticleColName", m_MCParticleColName,
           "MCParticle collection name.", std::string(""));
  m_Initialized = false;
}
 
EvtGenDecayModule::~EvtGenDecayModule()
{
}
 
void EvtGenDecayModule::initialize()
{
  StoreArray<MCParticle> mcParticles(m_MCParticleColName);
  mcParticles.isRequired();
  const std::string defaultDecFile =
    FileSystem::findFile("decfiles/dec/DECAY_BELLE2.DEC", true);
  if (m_DecFile.empty()) {
    B2ERROR("No global decay file defined, please make sure "
            "the parameter 'DecFile' is set correctly.");
    return;
  }
  if (defaultDecFile.empty()) {
    B2WARNING("Cannot find default decay file");
  } else if (defaultDecFile != m_DecFile) {
    B2INFO("Using non-standard DECAY file \"" << m_DecFile << "\"");
  }
}
 
void EvtGenDecayModule::beginRun()
{
}
 
void EvtGenDecayModule::event()
{
  int i, n;
  if (m_BeamParameters.hasChanged()) {
    if (!m_Initialized) {
      initializeGenerator();
    } else {
      B2FATAL("EvtGenDecayModule::event(): BeamParameters have changed within "
              "a job, this is not supported for EvtGen!");
    }
  }
  m_Graph.clear();
  m_Graph.loadList(m_MCParticleColName);
  n = m_Graph.size();
  for (i = 0; i < n; i++) {
    bool decay = true;
    MCParticleGraph::GraphParticle* graphParticle = &m_Graph[i];
 
    if (graphParticle->isInitial())
      decay = false;
    else if (graphParticle->getNDaughters() > 0)
      decay = false;
    else if (m_DecayableParticles.find(graphParticle->getPDG()) ==
             m_DecayableParticles.end())
      decay = false;
    if (decay)
      m_EvtGenInterface.simulateDecay(m_Graph, *graphParticle);
  }
  m_Graph.generateList(
    m_MCParticleColName,
    MCParticleGraph::c_clearParticles | MCParticleGraph::c_setDecayInfo |
    MCParticleGraph::c_checkCyclic);
}
 
void EvtGenDecayModule::endRun()
{
}
 
void EvtGenDecayModule::terminate()
{
}
 
void EvtGenDecayModule::initializeGenerator()
{
  int i, n;
  EvtId id;
  EvtDecayTable* decayTable;
  m_EvtGenInterface.setup(m_DecFile, "", m_UserDecFile);
  decayTable = EvtDecayTable::getInstance();
  n = EvtPDL::entries();
  for (i = 0; i < n; i++) {
    id = EvtPDL::getEntry(i);
    if (decayTable->getNModes(id) > 0)
      m_DecayableParticles.insert(EvtPDL::getStdHep(id));
  }
}