TauTruthMatchingTool.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
// Local include(s)
#include "TauAnalysisTools/TauTruthMatchingTool.h"
#include "TauAnalysisTools/HelperFunctions.h"
 
using namespace TauAnalysisTools;
 
//=================================PUBLIC-PART==================================
//______________________________________________________________________________
TauTruthMatchingTool::TauTruthMatchingTool( const std::string& name )
  : BuildTruthTaus(name)
  , m_accPtVis("pt_vis")
  , m_accEtaVis("eta_vis")
  , m_accPhiVis("phi_vis")
  , m_accMVis("m_vis")
{}
 
//______________________________________________________________________________
StatusCode TauTruthMatchingTool::initialize()
{
  ATH_MSG_INFO( "Initializing TauTruthMatchingTool" );
 
  // configure BuildTruthTaus in truth matching mode, not truth tau building mode
  TauTruthMatchingTool::BuildTruthTaus::setTruthMatchingMode();
 
  if (TauTruthMatchingTool::BuildTruthTaus::initialize().isFailure())
  {
    ATH_MSG_FATAL("Failed initializing BuildTruthTaus");
    return StatusCode::FAILURE;
  }
  return StatusCode::SUCCESS;
}
 
//______________________________________________________________________________
std::unique_ptr<TauTruthMatchingTool::ITruthTausEvent> TauTruthMatchingTool::getEvent() const
{
  const EventContext& ctx = Gaudi::Hive::currentContext();
  auto truthTausEvent = std::make_unique<TruthTausEvent>();
  if (retrieveTruthTaus(*truthTausEvent, ctx).isFailure()) {
    truthTausEvent.reset();
  }
  return truthTausEvent;
}
 
//______________________________________________________________________________
const xAOD::TruthParticle* TauTruthMatchingTool::getTruth(const xAOD::TauJet& xTau)
{
  return getTruth (xTau, m_truthTausEvent);
}
 
 
const xAOD::TruthParticle* TauTruthMatchingTool::getTruth(const xAOD::TauJet& xTau,
                              ITruthTausEvent& itruthTausEvent) const
{
  TruthTausEvent& truthTausEvent = dynamic_cast<TruthTausEvent&> (itruthTausEvent);
  const EventContext& ctx = Gaudi::Hive::currentContext();
  if (retrieveTruthTaus(truthTausEvent, ctx).isFailure())
    return nullptr;
 
  if (findTruthTau(xTau, truthTausEvent).isFailure())
    ATH_MSG_WARNING("There was a failure in finding the matched truth tau");
 
  static const SG::ConstAccessor<char> accIsTruthMatched("IsTruthMatched");
  static const SG::ConstAccessor< ElementLink< xAOD::TruthParticleContainer >  > accTruthParticleLink("truthParticleLink");
 
  // derivations may drop IsTruthMatched, redecorate using truthParticleLink (this assumes links to truth leptons are preserved, i.e. TruthTaus, TruthElectron, TruthMuon)
  if ( !(*m_bIsTruthMatchedAvailable.ptr()) && (*m_bIsTruthParticleLinkAvailable.ptr())) {
    ATH_MSG_DEBUG("TauJetContainer has truthParticleLink available while IsTruthMatched not available. Re-evaluate IsTruthMatched");
    static const SG::Decorator<char> decIsTruthMatched("IsTruthMatched");
    if (accTruthParticleLink(xTau)) {
      decIsTruthMatched(xTau) = (char)true;
    } else {
      decIsTruthMatched(xTau) = (char)false;
    }
  }
  
  // if matched to a truth particle return its pointer, else return a null pointer
  if (static_cast<bool>(accIsTruthMatched(xTau)))
    {
      if (accTruthParticleLink(xTau).isValid())
      {
        return *accTruthParticleLink(xTau);
      }
      else
      {
        ATH_MSG_WARNING("ElementLink to TruthParticle is not valid.");
        return nullptr;
      }
    }
 
  return nullptr;
}
 
//______________________________________________________________________________
std::vector<const xAOD::TruthParticle*> TauTruthMatchingTool::getTruth(const std::vector<const xAOD::TauJet*>& vTaus)
{
  std::vector<const xAOD::TruthParticle*> vTruths;
  for (auto xTau : vTaus)
    vTruths.push_back(getTruth(*xTau));
  return vTruths;
}

//                              Wrapper functions                             //
 
//______________________________________________________________________________
TLorentzVector TauTruthMatchingTool::getTruthTauP4Vis(const xAOD::TauJet& xTau)
{
  const xAOD::TruthParticle* xTruthTau = getTruth(xTau);
  TLorentzVector vTLV;
  if (xTruthTau == nullptr)
  {
    ATH_MSG_INFO("no truth particle was found, returning TLorentzVector with all values equal to 0");
  } else {
    vTLV = getTruthTauP4Vis(*xTruthTau);      
  }
  return vTLV;
}
 
//______________________________________________________________________________
TLorentzVector TauTruthMatchingTool::getTruthTauP4Vis(const xAOD::TruthParticle& xTruthTau) const
{
  TLorentzVector vTLV;
  static const SG::ConstAccessor<double> acc ("pt_vis");
  if (!acc.isAvailable(xTruthTau))
    return vTLV;
  vTLV.SetPtEtaPhiM(
    m_accPtVis(xTruthTau),
    m_accEtaVis(xTruthTau),
    m_accPhiVis(xTruthTau),
    m_accMVis(xTruthTau));
  return vTLV;
}
 
//______________________________________________________________________________
TLorentzVector TauTruthMatchingTool::getTruthTauP4Invis(const xAOD::TauJet& xTau)
{
  const xAOD::TruthParticle* xTruthTau = getTruth(xTau);
  TLorentzVector vTLV;
  if (xTruthTau == nullptr)
  {
    ATH_MSG_INFO("no truth particle was found, returning TLorentzVector with all values equal to 0");
  } else {
    vTLV = getTruthTauP4Invis(*xTruthTau);
  } 
  return vTLV; 
}
 
//______________________________________________________________________________
TLorentzVector TauTruthMatchingTool::getTruthTauP4Invis(const xAOD::TruthParticle& xTruthTau) const
{
  TLorentzVector vTLV;
 
  static const SG::ConstAccessor<double> accPtInvis("pt_invis");
  static const SG::ConstAccessor<double> accEtaInvis("eta_invis");
  static const SG::ConstAccessor<double> accPhiInvis("phi_invis");
  static const SG::ConstAccessor<double> accMInvis("m_invis");
 
  if (!accPtInvis.isAvailable(xTruthTau))
    return vTLV;
  vTLV.SetPtEtaPhiM(
    accPtInvis(xTruthTau),
    accEtaInvis(xTruthTau),
    accPhiInvis(xTruthTau),
    accMInvis(xTruthTau));
  return vTLV;
}
 
//______________________________________________________________________________
TauAnalysisTools::TruthMatchedParticleType TauTruthMatchingTool::getTruthParticleType(const xAOD::TauJet& xTau)
{
  return TauAnalysisTools::getTruthParticleType(xTau);
}
 
//______________________________________________________________________________
bool TauTruthMatchingTool::matchTruthLeptonicTauDecay(const xAOD::IParticle* p, const xAOD::TruthParticleContainer* truth_taus)
{
  // input check
  if (p->type() != xAOD::Type::Muon && p->type() != xAOD::Type::Electron)
     return false;
 
  // loop over truth_tau container
  for (auto truth_tau : *truth_taus) {
     if (!truth_tau->isTau()) {
        continue;
     }
     static const SG::ConstAccessor<char> accIsHadronicTau ("IsHadronicTau");
     if( accIsHadronicTau(*truth_tau)){
        continue;
     }
 
     static const SG::ConstAccessor<std::vector<int> > accDecayModeVector("DecayModeVector");
     if (accDecayModeVector.isAvailable(*truth_tau))
     { 
        std::vector<int> vDecayMode = accDecayModeVector(*truth_tau);        
        for (auto decayMode : vDecayMode) {
           if (p->type() == xAOD::Type::Electron) {
              if (fabs(decayMode) != 11)
                 continue;
           } else if (p->type() == xAOD::Type::Muon) {
              if (fabs(decayMode) != 13)
                 continue;
           }
           TLorentzVector vis = getTruthTauP4Vis(*truth_tau);
       if (vis.DeltaR(p->p4()) < 0.2) {
              return true; 
       }
        }
     }
  }
  // matching not found
  return false;
}
 
//______________________________________________________________________________
int TauTruthMatchingTool::getNTauDecayParticles(const xAOD::TauJet& xTau, int iPdgId, bool bCompareAbsoluteValues) 
{
  const xAOD::TruthParticle* xTruthTau = getTruth(xTau);
  if (xTruthTau == nullptr)
  {
    ATH_MSG_DEBUG("no truth particle was found, return 0");
    return 0;
  }
  static const SG::ConstAccessor<std::vector<int> > accDecayModeVector("DecayModeVector");
  if (!accDecayModeVector.isAvailable(*xTruthTau))
  {
    ATH_MSG_INFO("found truth particle is not a truth tau, return 0");
    return 0;
  }
  return getNTauDecayParticles(*xTruthTau,iPdgId, bCompareAbsoluteValues);
}
 
//______________________________________________________________________________
int TauTruthMatchingTool::getNTauDecayParticles(const xAOD::TruthParticle& xTruthTau, int iPdgId, bool bCompareAbsoluteValues) const
{
  int iNum = 0;
  static const SG::ConstAccessor<std::vector<int> > accDecayModeVector("DecayModeVector");
  if (!accDecayModeVector.isAvailable(xTruthTau))
  {
    ATH_MSG_WARNING("passed truth particle is not a truth tau, return 0");
    return 0;
  }
 
  for(auto iPdgId2 : accDecayModeVector(xTruthTau))
    if (!bCompareAbsoluteValues)
    {
      if (iPdgId2 == iPdgId) iNum++;
    }
    else
    {
      if (std::abs(iPdgId2) == std::abs(iPdgId)) iNum++;
    }
  return iNum;
}
 
//______________________________________________________________________________
xAOD::TauJetParameters::DecayMode TauTruthMatchingTool::getDecayMode(const xAOD::TauJet& xTau)
{
  const xAOD::TruthParticle* xTruthTau = getTruth(xTau);
  if (xTruthTau == nullptr)
  {
    ATH_MSG_DEBUG("no truth particle was found, return Mode_Error");
    return xAOD::TauJetParameters::Mode_Error;
  }
  static const SG::ConstAccessor<size_t> accNumCharged("numCharged");
  if (!accNumCharged.isAvailable(*xTruthTau))
  {
    ATH_MSG_INFO("found truth particle is not a truth tau, return Mode_Error");
    return xAOD::TauJetParameters::Mode_Error;
  }
  return getDecayMode(*xTruthTau);
}
 
//______________________________________________________________________________
xAOD::TauJetParameters::DecayMode TauTruthMatchingTool::getDecayMode(const xAOD::TruthParticle& xTruthTau) const
{
  static const SG::ConstAccessor<size_t> accNumCharged("numCharged");
  if (!accNumCharged.isAvailable(xTruthTau))
  {
    ATH_MSG_WARNING("passed truth particle is not a truth tau, return Mode_Error");
    return xAOD::TauJetParameters::Mode_Error;
  }
 
  int iCharged = getNTauDecayParticles(xTruthTau,MC::PIPLUS, true) + getNTauDecayParticles(xTruthTau,MC::KPLUS, true);
  int iNeutral = getNTauDecayParticles(xTruthTau,MC::PI0, true);
  if (iCharged == 1)
  {
    if (iNeutral == 0) return xAOD::TauJetParameters::DecayMode::Mode_1p0n;
    if (iNeutral == 1) return xAOD::TauJetParameters::DecayMode::Mode_1p1n;
    if (iNeutral >= 2) return xAOD::TauJetParameters::DecayMode::Mode_1pXn;
  }
  else if (iCharged == 3)
  {
    if (iNeutral == 0) return xAOD::TauJetParameters::DecayMode::Mode_3p0n;
    if (iNeutral >= 1) return xAOD::TauJetParameters::DecayMode::Mode_3pXn;
  }
 
  if (iCharged == 2 or iCharged == 4 or iCharged == 5)
    return xAOD::TauJetParameters::DecayMode::Mode_Other;
  if (iCharged == 0 or iCharged >=6)
    return xAOD::TauJetParameters::DecayMode::Mode_NotSet;
 
  // if you got here, something should have gone wrong
  return xAOD::TauJetParameters::DecayMode::Mode_Error;
}

//                                 Private Part                               //
 
//______________________________________________________________________________
StatusCode TauTruthMatchingTool::findTruthTau(const xAOD::TauJet& xTau,
                                              TruthTausEvent& truthTausEvent) const
{
  // check if decorations were already added to the first passed tau
  if (!m_bIsTruthMatchedAvailable.isValid()) {
    static const SG::ConstAccessor<char> accIsTruthMatched("IsTruthMatched");
    m_bIsTruthMatchedAvailable.set (accIsTruthMatched.isAvailable(xTau));
  }
  // check if decorations were already added to the first passed tau
  if (!m_bIsTruthParticleLinkAvailable.isValid()) {
    static const SG::ConstAccessor<ElementLink< xAOD::TruthParticleContainer > >
      accTruthParticleLink("truthParticleLink");
    m_bIsTruthParticleLinkAvailable.set (accTruthParticleLink.isAvailable(xTau));
  }
 
  if (*m_bIsTruthMatchedAvailable.ptr() || *m_bIsTruthParticleLinkAvailable.ptr()) {
    if (!m_bForceCheckTruthMatch) return StatusCode::SUCCESS;
  }
 
  // only search for truth taus once
 
  // need to be reviewed
 
  if (m_bTruthTauAvailable)
    return checkTruthMatch(xTau, *truthTausEvent.m_xTruthTauContainerConst, truthTausEvent);
  else
    return checkTruthMatch(xTau, *truthTausEvent.m_xTruthTauContainer, truthTausEvent);
}
 
//______________________________________________________________________________
StatusCode TauTruthMatchingTool::checkTruthMatch (const xAOD::TauJet& xTau, const xAOD::TruthParticleContainer& xTruthTauContainer, const TruthTausEvent& truthTausEvent) const
{
  const xAOD::TruthParticle* xTruthMatch = nullptr;
  const xAOD::Jet* xTruthJetMatch = nullptr;
  TruthMatchedParticleType eTruthMatchedParticleType = Unknown;
  static const SG::Decorator<char> decIsTruthMatched("IsTruthMatched");
  static const SG::Decorator< ElementLink< xAOD::JetContainer > > decTruthJetLink("truthJetLink");
  
  for (auto xTruthTauIt : xTruthTauContainer)
  {
    TLorentzVector vTruthVisTLV;
    vTruthVisTLV.SetPtEtaPhiM(m_accPtVis(*xTruthTauIt),
                              m_accEtaVis(*xTruthTauIt),
                              m_accPhiVis(*xTruthTauIt),
                              m_accMVis(*xTruthTauIt));
    if (xTau.p4().DeltaR(vTruthVisTLV) <= m_dMaxDeltaR)
    {
      static const SG::ConstAccessor<char> accIsHadronicTau("IsHadronicTau");
      if (static_cast<bool>(accIsHadronicTau(*xTruthTauIt)))
        eTruthMatchedParticleType = TruthHadronicTau;
      else
        eTruthMatchedParticleType = TruthLeptonicTau;
 
      xTruthMatch = xTruthTauIt;
      break;
    }
  }
 
  double dPtMax = 0.;
  if (!xTruthMatch and truthTausEvent.m_xTruthMuonContainerConst)
  {
    dPtMax = 0.;
    for (auto xTruthMuonIt : *truthTausEvent.m_xTruthMuonContainerConst)
    {
      if (xTau.p4().DeltaR(xTruthMuonIt->p4()) <= m_dMaxDeltaR)
      {
        if (xTruthMuonIt->pt()<dPtMax)
          continue;
        eTruthMatchedParticleType = TruthMuon;
        xTruthMatch = xTruthMuonIt;
        dPtMax = xTruthMuonIt->pt();
      }
    }
  }
 
  if (!xTruthMatch and truthTausEvent.m_xTruthElectronContainerConst)
  {
    dPtMax = 0.;
    for (auto xTruthElectronIt : *truthTausEvent.m_xTruthElectronContainerConst)
    {
      if (xTau.p4().DeltaR(xTruthElectronIt->p4()) <= m_dMaxDeltaR)
      {
        if (xTruthElectronIt->pt()<dPtMax)
          continue;
        eTruthMatchedParticleType = TruthElectron;
        xTruthMatch = xTruthElectronIt;
        dPtMax = xTruthElectronIt->pt();
      }
    }
  }
 
  if (truthTausEvent.m_xTruthJetContainerConst)
  {
    dPtMax = 0.;
    for (auto xTruthJetIt : *truthTausEvent.m_xTruthJetContainerConst)
    {
      if (xTau.p4().DeltaR(xTruthJetIt->p4()) <= m_dMaxDeltaR)
      {
        if (xTruthJetIt->pt()<dPtMax)
          continue;
        xTruthJetMatch = xTruthJetIt;
        dPtMax = xTruthJetIt->pt();
      }
    }
  }
 
  if (xTruthMatch)
    decIsTruthMatched(xTau) = (char)true;
  else
    decIsTruthMatched(xTau) = (char)false;
 
  if (xTruthJetMatch)
  {
    ElementLink < xAOD::JetContainer > lTruthParticleLink(xTruthJetMatch, *truthTausEvent.m_xTruthJetContainerConst);
    decTruthJetLink(xTau) = lTruthParticleLink;
  }
  else
  {
    ElementLink < xAOD::JetContainer > lTruthParticleLink;
    decTruthJetLink(xTau) = lTruthParticleLink;
  }
 
  // create link to the original TruthParticle
  static const SG::Decorator< ElementLink< xAOD::TruthParticleContainer > > decTruthParticleLink("truthParticleLink");
 
  if (xTruthMatch)
  {
    if (eTruthMatchedParticleType == TruthHadronicTau or eTruthMatchedParticleType == TruthLeptonicTau)
    {
      ElementLink < xAOD::TruthParticleContainer > lTruthParticleLink(xTruthMatch, xTruthTauContainer);
      decTruthParticleLink(xTau) = lTruthParticleLink;
    }
    else if (eTruthMatchedParticleType == TruthMuon)
    {
      ElementLink < xAOD::TruthParticleContainer > lTruthParticleLink(xTruthMatch, *truthTausEvent.m_xTruthMuonContainerConst);
      decTruthParticleLink(xTau) = lTruthParticleLink;
    }
    else if (eTruthMatchedParticleType == TruthElectron)
    {
      ElementLink < xAOD::TruthParticleContainer > lTruthParticleLink(xTruthMatch, *truthTausEvent.m_xTruthElectronContainerConst);
      decTruthParticleLink(xTau) = lTruthParticleLink;
    }
  }
  else
  {
    ElementLink < xAOD::TruthParticleContainer > lTruthParticleLink;
    decTruthParticleLink(xTau) = lTruthParticleLink;
  }
 
  return StatusCode::SUCCESS;
}
 

StatusCode
TauTruthMatchingTool::lockDecorations (const xAOD::TauJetContainer& taus) const
{
  xAOD::TauJetContainer& taus_nc ATLAS_THREAD_SAFE = const_cast<xAOD::TauJetContainer&> (taus);
  static const SG::Decorator<char> decIsTruthMatched("IsTruthMatched");
  static const SG::Decorator< ElementLink< xAOD::JetContainer > > decTruthJetLink("truthJetLink");
  static const SG::Decorator< ElementLink< xAOD::TruthParticleContainer > > decTruthParticleLink("truthParticleLink");
  taus_nc.lockDecoration (decIsTruthMatched.auxid());
  taus_nc.lockDecoration (decTruthJetLink.auxid());
  taus_nc.lockDecoration (decTruthParticleLink.auxid());
  return StatusCode::SUCCESS;
}