DiphotonVertexDecorator.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/

// DiphotonVertexDecorator.cxx
// To add the diphoton vertex to the evtStore
 
#include "DerivationFrameworkHiggs/DiphotonVertexDecorator.h"
#include <vector>
#include <string>
#include "TString.h"
 
 
#include "xAODCore/ShallowCopy.h"
#include "xAODEventInfo/EventInfo.h"
#include "xAODTracking/TrackingPrimitives.h"
#include "xAODTracking/VertexContainer.h"
#include "AthContainers/ConstDataVector.h"
// For DeltaR
#include "FourMomUtils/xAODP4Helpers.h"
#include "AthContainers/Decorator.h"
 
typedef ElementLink<xAOD::PhotonContainer> phlink_t;
 
// Athena initialize
StatusCode DerivationFramework::DiphotonVertexDecorator::initialize()
{
  ATH_CHECK( m_photonVertexSelectionTool.retrieve() );
  ATH_CHECK( m_primaryVertexKey.initialize() );
  ATH_CHECK( m_photonKey.initialize() );
  ATH_CHECK( m_diphotonVertexKey.initialize() );
  ATH_CHECK( m_FEContainerHandleKey.initialize() );
  return StatusCode::SUCCESS;
}
 
 
StatusCode DerivationFramework::DiphotonVertexDecorator::addBranches(const EventContext& ctx) const
{
  ATH_MSG_DEBUG( "DiphotonVertexDecorator::AddingBranches" );
 
  SG::ReadHandle<xAOD::VertexContainer> PV (m_primaryVertexKey, ctx);
 
  if (!PV->empty() && PV->at(0)) {
    ATH_MSG_DEBUG( "Default PV " << PV->at(0) << ", type = " << PV->at(0)->vertexType() << " , z = " << PV->at(0)->z()  );
  }
 
  // Select the two highest pt photons that pass a preselection
 
  SG::ReadHandle<xAOD::PhotonContainer> photons (m_photonKey, ctx);
  const xAOD::Photon *ph1 = nullptr, *ph2 = nullptr;
 
  for (const xAOD::Photon* ph: *photons)
  {
    if (!PhotonPreselect(ph)) continue;
    if (not ph1 or ph->pt() > ph1->pt()) // new leading photon
    {
      ph2 = ph1;
      ph1 = ph;
    }
    else if (not ph2 or ph->pt() > ph2->pt()) ph2 = ph; // new subleading photon
  }
 
  const ConstDataVector< xAOD::PhotonContainer > vertexPhotons = {ph1, ph2};
 
  CP::IPhotonVertexSelectionTool::FailType vertexFailType;
  CP::IPhotonVertexSelectionTool::yyVtxType yyvertexVtxType = CP::IPhotonVertexSelectionTool::Unknown;
 
  ATH_CHECK( m_photonVertexSelectionTool->decorateInputs(*(vertexPhotons.asDataVector()), &vertexFailType) );
 
  // Get the photon vertex if possible
  std::vector<std::pair<const xAOD::Vertex*, float> > vxResult;
  const xAOD::Vertex *newPV = nullptr;
 
  SG::ReadHandle<xAOD::FlowElementContainer> FEHandle(m_FEContainerHandleKey, ctx);
  SG::Decorator<char> passORDec("passOR");
  for(const auto *const fe : *FEHandle) passORDec(*fe) = true;
 
  if (ph1 and ph2)
  {
    vxResult = m_photonVertexSelectionTool->getVertex( *( vertexPhotons.asDataVector()) , m_ignoreConv, true, &yyvertexVtxType, &vertexFailType );
    if(!vxResult.empty()) {
      newPV = vxResult[0].first; //output of photon vertex selection tool must be sorted according to score
    }
    ATH_CHECK(matchFlowElement(ph1,&*FEHandle));
    ATH_CHECK(matchFlowElement(ph2,&*FEHandle));
  }
 
  // Decorate the vertices with the NN score
  ATH_MSG_DEBUG("PhotonVertexSelection returns vertex " << newPV << " " << (newPV? Form(" with z = %g", newPV->z()) : "") );
  // Create shallow copy of the PrimaryVertices container
  xAOD::ShallowCopyResult_t<xAOD::VertexContainer> HggPV =
    xAOD::shallowCopy( *PV, ctx );
  HggPV.second->setShallowIO(false);
 
  SG::WriteHandle<xAOD::VertexContainer> vertexContainer(m_diphotonVertexKey, ctx);
  ATH_CHECK(vertexContainer.recordNonConst(std::move(HggPV.first),
                                           std::move(HggPV.second)));
 
 
  static const SG::Accessor<float> vertexScoreAcc("vertexScore");
  static const SG::Accessor<int> vertexFailTypeAcc("vertexFailType");
  static const SG::Accessor<int> vertexCaseAcc("vertexCase");
  static const SG::Accessor<phlink_t> leadingPhotonLinkAcc("leadingPhotonLink");
  static const SG::Accessor<phlink_t> subleadingPhotonLinkAcc("subleadingPhotonLink");
 
  if (newPV) {
    //loop over vertex container; shallow copy has the same order
    for (unsigned int iPV=0; iPV<PV->size(); iPV++) {
      const auto *vx = PV->at(iPV);
      auto yyvx = vertexContainer->at(iPV);
      //reset vertex type
      if (vx == newPV) {
        //is this the diphoton primary vertex returned from the tool?
        yyvx->setVertexType( xAOD::VxType::PriVtx );
      } else if ( vx->vertexType()==xAOD::VxType::PriVtx || vx->vertexType()==xAOD::VxType::PileUp ) {
        //not overriding the type of dummy vertices of type 0 (NoVtx)
        yyvx->setVertexType( xAOD::VxType::PileUp );
      }
      //decorate score
      for (const auto& vxR: vxResult) {
        //find vertex in output from photonVertexSelectionTool
        if ( vx == vxR.first ) {
          vertexScoreAcc(*yyvx) = vxR.second;
          vertexFailTypeAcc(*yyvx) = vertexFailType;
          vertexCaseAcc(*yyvx) = yyvertexVtxType;
          leadingPhotonLinkAcc(*yyvx) = phlink_t(*photons, ph1->index());
          subleadingPhotonLinkAcc(*yyvx) = phlink_t(*photons, ph2->index());
          break;
        }
      }
    }
  }
  else {
    //no vertex returned by photonVertexSelectionTool, decorate default PV with fit information
    xAOD::VertexContainer::iterator yyvx_itr;
    xAOD::VertexContainer::iterator yyvx_end = vertexContainer->end();
    for(yyvx_itr = vertexContainer->begin(); yyvx_itr != yyvx_end; ++yyvx_itr ) {
      if ( (*yyvx_itr)->vertexType()==xAOD::VxType::PriVtx ) {
        vertexScoreAcc(**yyvx_itr) = -9999;
        vertexFailTypeAcc(**yyvx_itr) = vertexFailType;
        vertexCaseAcc(**yyvx_itr) = yyvertexVtxType;
        leadingPhotonLinkAcc(**yyvx_itr) = (phlink_t()) ;
        subleadingPhotonLinkAcc(**yyvx_itr) = (phlink_t());
      }
    }
  }
 
 
  if( !evtStore()->transientContains< xAOD::VertexContainer >( m_diphotonVertexKey.key() ) ){
    ATH_MSG_WARNING("Unable to find transient xAOD::VertexContainer, \"" << m_diphotonVertexKey.key() << "\"");
  }
 
  return StatusCode::SUCCESS;
}
 
bool DerivationFramework::DiphotonVertexDecorator::PhotonPreselect(const xAOD::Photon *ph) const
{
 
  if (!ph) return false;
 
  if (!ph->isGoodOQ(34214)) return false;
 
  bool val(false);
  bool defined(false);
 
  static const SG::ConstAccessor<char> DFCommonPhotonsIsEMLooseAcc("DFCommonPhotonsIsEMLoose");
  if(DFCommonPhotonsIsEMLooseAcc.isAvailable(*ph)){
    defined = true;
    val = static_cast<bool>(DFCommonPhotonsIsEMLooseAcc(*ph));
  }
  else{
    defined = ph->passSelection(val, "Loose");
  }
 
  if(!defined || !val) return false;
 
  // veto topo-seeded clusters
  if (ph->author(xAOD::EgammaParameters::AuthorCaloTopo35)) return false;
 
  // Check which variable versions are best...
  const xAOD::CaloCluster *caloCluster(ph->caloCluster());
  double eta = std::abs(caloCluster->etaBE(2));
 
  if (eta > m_maxEta) return false;
  if (m_removeCrack && 1.37 <= eta && eta <= 1.52) return false;
 
  if (ph->pt() < m_minPhotonPt) return false;
 
  return true;
 
}
 
StatusCode DerivationFramework::DiphotonVertexDecorator::matchFlowElement(const xAOD::Photon* eg,const xAOD::FlowElementContainer *feCont) const {
  const xAOD::IParticle* swclus = eg->caloCluster();
 
  // Preselect FEs based on proximity: dR<0.4
  std::vector<const xAOD::FlowElement*> nearbyFE;
  nearbyFE.reserve(20);
  for(const auto *const fe : *feCont) {
    if(xAOD::P4Helpers::isInDeltaR(*fe, *swclus, 0.4, true)) {
      if( ( !fe->isCharged() && fe->e() > FLT_MIN )) nearbyFE.push_back(fe);
    } // DeltaR check
  } // FE loop
 
  SG::Decorator<char> passORDec("passOR");
 
  double eg_cl_e = swclus->e();
  bool doSum = true;
  double sumE_fe = 0.;
  const xAOD::IParticle* bestbadmatch = nullptr;
  std::sort(nearbyFE.begin(),nearbyFE.end(),greaterPtFlowElement);
  for(const auto& fe : nearbyFE) {
    if(!xAOD::P4Helpers::isInDeltaR(*fe, *swclus, m_tcMatch_dR, true)) {continue;}
    // Handle neutral FEs like topoclusters
    double fe_e = fe->e();
    // skip cluster if it's above our bad match threshold or outside the matching radius
    if(fe_e>m_tcMatch_maxRat*eg_cl_e) {
      ATH_MSG_VERBOSE("Reject topocluster in sum. Ratio vs eg cluster: " << (fe_e/eg_cl_e));
      if( !bestbadmatch || (std::abs(fe_e/eg_cl_e-1.) < std::abs(bestbadmatch->e()/eg_cl_e-1.)) ) bestbadmatch = fe;
      continue;
    }
 
    ATH_MSG_VERBOSE("E match with new nFE: " << std::abs(sumE_fe+fe_e - eg_cl_e) / eg_cl_e);
    if( (doSum = std::abs(sumE_fe+fe_e-eg_cl_e) < std::abs(sumE_fe - eg_cl_e)) ) {
       passORDec(*fe) = false;
      sumE_fe += fe_e;
    } // if we will retain the topocluster
    else {break;}
  } // loop over nearby clusters
  if(sumE_fe<FLT_MIN && bestbadmatch) {
    passORDec(*bestbadmatch) = false;
  }
 
  return StatusCode::SUCCESS;
}