JetCalibrationDecoratorAlg.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "FlavorTagDiscriminants/JetCalibrationDecoratorAlg.h"
#include "StoreGate/ReadHandle.h"
#include "StoreGate/WriteDecorHandle.h"
#include "xAODCore/ShallowCopy.h"
 
 
namespace FlavorTagDiscriminants {
 
  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
    std::pair<std::unique_ptr<xAOD::JetContainer>,
              std::unique_ptr<xAOD::ShallowAuxContainer>> shallowCopy =
      xAOD::shallowCopyContainer(*jets, ctx);
    std::unique_ptr<xAOD::JetContainer>& copyUP = shallowCopy.first;
    [[maybe_unused]] std::unique_ptr<xAOD::ShallowAuxContainer>& auxUP =
      shallowCopy.second;
 
    // 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;
  }
 
} // namespace FlavorTagDiscriminants