JetCalibrationDecoratorAlg.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "JetCalibrationDecoratorAlg.h"
#include "StoreGate/ReadHandle.h"
#include "StoreGate/WriteDecorHandle.h"
#include "xAODCore/ShallowCopy.h"
 
 
JetCalibrationDecoratorAlg::JetCalibrationDecoratorAlg(
  const std::string& name, ISvcLocator* loc)
  : AthReentrantAlgorithm(name, loc)
{
  declareProperty("JetCalibrationTool", m_calibTool, "Jet calibration tool");
}
 
StatusCode JetCalibrationDecoratorAlg::initialize() {
  ATH_CHECK(m_calibTool.retrieve());
  ATH_CHECK(m_jetKey.initialize());
  ATH_CHECK(m_ptCalibKey.initialize());
  ATH_CHECK(m_etaCalibKey.initialize());
  ATH_CHECK(m_massCalibKey.initialize());
  ATH_CHECK(m_phiCalibKey.initialize());
  return StatusCode::SUCCESS;
}
 
StatusCode JetCalibrationDecoratorAlg::execute(
  const EventContext& ctx) const
{
  SG::ReadHandle<xAOD::JetContainer> jets(m_jetKey, ctx);
  ATH_CHECK(jets.isValid());
 
  SG::WriteDecorHandle<xAOD::JetContainer, float> ptDec(
    m_ptCalibKey, ctx);
  SG::WriteDecorHandle<xAOD::JetContainer, float> etaDec(
    m_etaCalibKey, ctx);
  SG::WriteDecorHandle<xAOD::JetContainer, float> massDec(
    m_massCalibKey, ctx);
  SG::WriteDecorHandle<xAOD::JetContainer, float> phiDec(
    m_phiCalibKey, ctx);
 
  // Shallow-copy jets so calibration doesn't modify originals
  auto [copyUP, auxUP] = xAOD::shallowCopy(*jets, ctx);
 
  // Apply calibration to the copies
  ATH_CHECK(m_calibTool->modify(*copyUP));
 
  // Decorate originals with calibrated kinematics from copies
  for (size_t i = 0; i < jets->size(); ++i) {
    const xAOD::Jet& originalJet = *jets->at(i);
    const xAOD::Jet& calibratedJet = *copyUP->at(i);
 
    ptDec(originalJet) = calibratedJet.pt();
    etaDec(originalJet) = calibratedJet.eta();
    massDec(originalJet) = calibratedJet.m();
    phiDec(originalJet) = calibratedJet.phi();
  }
 
  return StatusCode::SUCCESS;
}