MuonGenParticleAssociationTool.cxx

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
// $Id$
#include "MuonGenParticleAssociationTool.h"
#include "xAODMuon/Muon.h"
#include "xAODTruth/TruthParticle.h"
#include "FourMomUtils/P4Helpers.h"
#include "AthenaKernel/errorcheck.h"
#include <cstdlib>
 
 
namespace D3PD {
 
 
MuonGenParticleAssociationTool::MuonGenParticleAssociationTool
  (const std::string& type,
   const std::string& name,
   const IInterface* parent)
    : Base (type, name, parent),
      m_classifier ("MCTruthClassifier")
{
  declareProperty ("Classifier", m_classifier, "Classifier tool instance.");
  declareProperty ("DRVar", m_drvar,
                   "If not empty, the variable name to use for DR.");
 
  m_dr = nullptr;
}
 
 
StatusCode MuonGenParticleAssociationTool::initialize()
{
  CHECK( Base::initialize() );
  CHECK( m_classifier.retrieve() );
  return StatusCode::SUCCESS;
}
 
 
StatusCode MuonGenParticleAssociationTool::book ()
{
  if (!m_drvar.empty())
    CHECK( addVariable (m_drvar, m_dr) );
  return StatusCode::SUCCESS;
}
 
 
const xAOD::TruthParticle*
MuonGenParticleAssociationTool::get (const xAOD::Muon& p)
{
  MCTruthPartClassifier::Info info;
  const xAOD::TruthParticle* out = nullptr;
  if (m_classifier->particleTruthClassifier (&p, &info).first !=
      MCTruthPartClassifier::Unknown)
  {
    out = info.genPart;
  }
 
  if (!m_drvar.empty()) {
    if (out)
      *m_dr = p.p4().DeltaR(out->p4());
    else
      *m_dr = -999;
  }
 
  return out;
}
 
 
} // namespace D3PD