KlongDecayReconstructorExpertModule.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.                  *
 **************************************************************************/
 
// Own header.
#include <analysis/modules/KlongDecayReconstructor/KlongDecayReconstructorExpertModule.h>
 
// framework aux
#include <framework/logging/Logger.h>
 
// decay descriptor
#include <analysis/DecayDescriptor/DecayDescriptorParticle.h>
 
// utilities
#include <analysis/DecayDescriptor/ParticleListName.h>
 
#include <Math/Vector4D.h>
#include <TMath.h>
 
#include <memory>
 
using namespace std;
using namespace Belle2;
 
//-----------------------------------------------------------------
//                 Register module
//-----------------------------------------------------------------
 
REG_MODULE(KlongDecayReconstructorExpert);
 
//-----------------------------------------------------------------
//                 Implementation
//-----------------------------------------------------------------
 
KlongDecayReconstructorExpertModule::KlongDecayReconstructorExpertModule() :
  Module(), m_pdgCode(0), m_isSelfConjugatedParticle(false)
 
{
  // set module description (e.g. insert text)
  setDescription(R"DOC(
This module is used to employ kinematic constraints to determine the momentum
of Klongs for two body B decays containing a K_L0 and something else. The
module creates a list of K_L0 candidates whose K_L0 momentum is reconstructed
by combining the reconstructed direction (from either the ECL or KLM) of the
K_L0 and kinematic constraints of the initial state.
                )DOC");
  setPropertyFlags(c_ParallelProcessingCertified);
 
  // Add parameters
  addParam("decayString", m_decayString,
           "Input DecayDescriptor string.");
  addParam("cut", m_cutParameter, "Selection criteria to be applied", std::string(""));
  addParam("maximumNumberOfCandidates", m_maximumNumberOfCandidates,
           "Don't reconstruct channel if more candidates than given are produced.", -1);
  addParam("decayMode", m_decayModeID, "User-specified decay mode identifier (saved in 'decayModeID' extra-info for each Particle)",
           0);
  addParam("writeOut", m_writeOut,
           "If true, the output ParticleList will be saved by RootOutput. If false, it will be ignored when writing the file.", false);
  addParam("recoList", m_recoList,
           "Suffix attached to the original K_L input list to identify the output list of the FindKlongMomentum module; this is the input for this module, if not defined it is set to '_reco' \n",
           std::string("_reco"));
 
}
 
void KlongDecayReconstructorExpertModule::initialize()
{
  m_particles.isRequired();
 
  // clear everything, initialize private members
  m_listName = "";
  m_generator = nullptr;
 
  // obtain the input and output particle lists from the decay string
  bool valid = m_decaydescriptor.init(m_decayString);
  if (!valid)
    B2ERROR("Invalid input DecayString: " << m_decayString);
 
  // Mother particle
  const DecayDescriptorParticle* mother = m_decaydescriptor.getMother();
 
  m_pdgCode = mother->getPDGCode();
  m_listName = mother->getFullName();
 
  m_antiListName = ParticleListName::antiParticleListName(m_listName);
  m_isSelfConjugatedParticle = (m_listName == m_antiListName);
 
  std::string newDecayString;
  std::string kListName;
  newDecayString = m_listName + " -> ";
 
  // Daughters
  bool k_check = false;
  int nProducts = m_decaydescriptor.getNDaughters();
  for (int i = 0; i < nProducts; ++i) {
    const DecayDescriptorParticle* daughter = m_decaydescriptor.getDaughter(i)->getMother();
    if (daughter->getPDGCode() == Const::Klong.getPDGCode()) {
      if (k_check)
        B2FATAL("More than one K_L is detected! This module accepts only one K_L in the final state.");
 
      StoreObjPtr<ParticleList>().isRequired(daughter->getFullName() + m_recoList);
      kListName = daughter->getFullName() + m_recoList;
      k_check = true;
    } else {
      StoreObjPtr<ParticleList>().isRequired(daughter->getFullName());
      newDecayString = newDecayString + daughter->getFullName() + " ";
    }
  }
 
  if (!k_check)
    B2FATAL("This module is meant to reconstruct decays with a K_L0 in the final state. There is no K_L0 in this decay!");
 
  newDecayString = newDecayString + kListName;
 
  m_generator = std::make_unique<ParticleGenerator>(newDecayString, m_cutParameter);
 
  DataStore::EStoreFlags flags = m_writeOut ? DataStore::c_WriteOut : DataStore::c_DontWriteOut;
  m_outputList.registerInDataStore(m_listName, flags);
  if (!m_isSelfConjugatedParticle) {
    m_outputAntiList.registerInDataStore(m_antiListName, flags);
  }
 
  m_cut = Variable::Cut::compile(m_cutParameter);
 
}
 
void KlongDecayReconstructorExpertModule::event()
{
  m_outputList.create();
  m_outputList->initialize(m_pdgCode, m_listName);
 
  if (!m_isSelfConjugatedParticle) {
    m_outputAntiList.create();
    m_outputAntiList->initialize(-1 * m_pdgCode, m_antiListName);
 
    m_outputList->bindAntiParticleList(*(m_outputAntiList));
  }
 
  m_generator->init();
 
  int numberOfCandidates = 0;
  while (m_generator->loadNext()) {
 
    Particle particle = m_generator->getCurrentParticle();
 
    bool is_physical = true;
 
    const std::vector<Particle*> daughters = particle.getDaughters();
 
    if (daughters.size() < 2)
      B2FATAL("Reconstructing particle as a daughter of a decay with less than 2 daughters!");
 
    if (daughters.size() > 3)
      B2FATAL("Higher multiplicity (>2) missing momentum decays not implemented yet!");
 
    int e_check = 0;
    ROOT::Math::PxPyPzEVector pDaughters;
    for (auto daughter : daughters) {
      if (daughter->getPDGCode() != Const::Klong.getPDGCode()) {
        pDaughters += daughter->get4Vector();
        e_check = daughter->getArrayIndex() + e_check * 100;
      }
    }
 
 
    ROOT::Math::PxPyPzEVector klDaughters;
    for (auto daughter : daughters) {
      if (daughter->getPDGCode() == Const::Klong.getPDGCode()) {
        klDaughters += daughter->get4Vector();
        if (e_check != daughter->getExtraInfo("permID")) {
          is_physical = false;
        }
      }
    }
    double m_b = particle.getPDGMass();
 
    ROOT::Math::PxPyPzEVector mom = pDaughters + klDaughters;
    mom.SetE(TMath::Sqrt(mom.P2() + m_b * m_b));
    if ((!isnan(mom.P())) && is_physical)
      particle.set4Vector(mom);
    if (isnan(mom.P()))
      is_physical = false;
 
    if (!m_cut->check(&particle))
      continue;
 
    if (!is_physical)
      continue;
 
    numberOfCandidates++;
 
    if (m_maximumNumberOfCandidates > 0 and numberOfCandidates > m_maximumNumberOfCandidates) {
      m_outputList->clear();
      break;
    }
 
    Particle* newParticle = m_particles.appendNew(particle);
 
    m_outputList->addParticle(newParticle);
    newParticle->addExtraInfo("decayModeID", m_decayModeID);
 
  } //while
 
} //event