TransverseMassSelectorAlg.cxx

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/*
   Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
 
 
#include "EventSelectionAlgorithms/TransverseMassSelectorAlg.h"
 
namespace CP {
 
  TransverseMassSelectorAlg::TransverseMassSelectorAlg(const std::string &name, ISvcLocator *pSvcLocator)
  : EL::AnaAlgorithm(name, pSvcLocator)
  {}
 
  StatusCode TransverseMassSelectorAlg::initialize() {
    ANA_CHECK(m_metHandle.initialize(m_systematicsList));
    ANA_CHECK(m_electronsHandle.initialize(m_systematicsList, SG::AllowEmpty));
    ANA_CHECK(m_electronSelection.initialize(m_systematicsList, m_electronsHandle, SG::AllowEmpty));
    ANA_CHECK(m_muonsHandle.initialize(m_systematicsList, SG::AllowEmpty));
    ANA_CHECK(m_muonSelection.initialize(m_systematicsList, m_muonsHandle, SG::AllowEmpty));
    ANA_CHECK(m_eventInfoHandle.initialize(m_systematicsList));
 
    ANA_CHECK(m_preselection.initialize(m_systematicsList, m_eventInfoHandle, SG::AllowEmpty));
    ANA_CHECK(m_decoration.initialize(m_systematicsList, m_eventInfoHandle));
    ANA_CHECK(m_systematicsList.initialize());
 
    m_signEnum = SignEnum::stringToOperator.at( m_sign );
 
    return StatusCode::SUCCESS;
  }
 
  StatusCode TransverseMassSelectorAlg::execute() {
    for (const auto &sys : m_systematicsList.systematicsVector()) {
      // retrieve the EventInfo
      const xAOD::EventInfo *evtInfo = nullptr;
      ANA_CHECK(m_eventInfoHandle.retrieve(evtInfo, sys));
 
      // default-decorate EventInfo
      m_decoration.setBool(*evtInfo, 0, sys);
 
      // check the preselection
      if (m_preselection && !m_preselection.getBool(*evtInfo, sys))
        continue;
 
      // retrieve the MET container
      const xAOD::MissingETContainer *met = nullptr;
      ANA_CHECK(m_metHandle.retrieve(met, sys));
      // retrieve the electron container
      const xAOD::IParticleContainer *electrons = nullptr;
      if (m_electronsHandle)
    ANA_CHECK(m_electronsHandle.retrieve(electrons, sys));
      // retrieve the electron container
      const xAOD::IParticleContainer *muons = nullptr;
      if (m_muonsHandle)
    ANA_CHECK(m_muonsHandle.retrieve(muons, sys));
 
      // apply the requested selection, compute the W boson transverse mass
      float etmiss_pt = (*met)[m_metTerm.value()]->met();
      float etmiss_phi = (*met)[m_metTerm.value()]->phi();
      float lep_pt, lep_phi;
      int lep_count = 0;
 
      if (m_electronsHandle) {
    for (const xAOD::IParticle *el : *electrons) {
      if (!m_electronSelection || m_electronSelection.getBool(*el, sys)){
        lep_pt = el->pt();
        lep_phi = el->phi();
        lep_count++;
        break;
      }
    }
      }
      if (m_muonsHandle) {
    for (const xAOD::IParticle *mu : *muons) {
      if (!m_muonSelection || m_muonSelection.getBool(*mu, sys)) {
        lep_pt = mu->pt();
        lep_phi = mu->phi();
        lep_count++;
        break;
      }
    }
      }
 
      // exit 1 if there were no leptons or 2 or more leptons in the event
      if (lep_count == 0){
        ATH_MSG_ERROR("No charged lepton in the event, cannot compute MWT!");
        return StatusCode::FAILURE;
      }
      if (lep_count > 1){
        ATH_MSG_ERROR("More than one lepton is associated with this event - cannot determine which is the W decay lepton.");
        return StatusCode::FAILURE;
      }
 
      float mwt = sqrt(2. * lep_pt * etmiss_pt * (1. - std::cos(lep_phi - etmiss_phi)));
 
      // calculate decision
      bool decision = SignEnum::checkValue(m_mwtref.value(), m_signEnum, mwt);
      m_decoration.setBool(*evtInfo, decision, sys);
    }
    return StatusCode::SUCCESS;
  }
} // namespace CP