e1hg_systematics.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "ElectronPhotonFourMomentumCorrection/e1hg_systematics.h"
 
#include <cmath>
#include <cstdlib>
 
#include "PathResolver/PathResolver.h"
#include "TAxis.h"
 
e1hg_systematics::e1hg_systematics(const std::string& filename) {
 
  m_file0 = TFile::Open(filename.c_str());
 
  for (Int_t ieta = 0; ieta < 8; ieta++) {
    char name[60];
    sprintf(name, "elec_%d", ieta);
    m_helec[ieta] = (TH1D*)m_file0->Get(name);
    sprintf(name, "unconv_%d", ieta);
    m_hphot[ieta] = (TH1D*)m_file0->Get(name);
    sprintf(name, "conv_%d", ieta);
    m_hphot2[ieta] = (TH1D*)m_file0->Get(name);
  }
 
  TAxis* aa = m_helec[0]->GetXaxis();
  m_etBins = aa->GetXbins();
}
 
//=========================================================================
e1hg_systematics::~e1hg_systematics() {
  m_file0->Close();
}
 
//============================================================================
// inputs are particle_type (0=elec, 1=reco unconv photon, 2=reco conv photon)
//            energy in MeV
//            eta
//
// returned value is alpha = DeltaE / E
//
double e1hg_systematics::getAlpha(int particle_type, double energy, double eta,
                                  bool interpolate) const {
 
  // cout << " in getDelta " << endl;
  if (particle_type < 0 || particle_type > 2)
    return 0.;
 
  float aeta = fabs(eta);
  int ieta = 0;
  if (aeta < 0.4)
    ieta = 0;
  else if (aeta < 0.8)
    ieta = 1;
  else if (aeta < 1.1)
    ieta = 2;
  else if (aeta < 1.37)
    ieta = 3;
  else if (aeta < 1.52)
    ieta = 4;
  else if (aeta < 1.80)
    ieta = 5;
  else if (aeta < 2.10)
    ieta = 6;
  else
    ieta = 7;
 
  double energyGeV = energy * 0.001;
  double et = energyGeV / std::cosh(eta);
 
  int ibinEt = m_etBins->GetSize() - 2;
  for (int i = 1; i < m_etBins->GetSize(); i++) {
    if (et < m_etBins->GetAt(i)) {
      ibinEt = i - 1;
      break;
    }
  }
 
  //   cout << " energy, et , ibinEt " << energyGeV << " " << et << " " <<
  //   ibinEt << endl;
 
  Double_t scale = 0.;
  // HACK: some ES model dependency needs to be introduced
  /*Default up to es2017_summer
    if (aeta<1.80) scale=0.;
    else if (aeta<2.3) scale = 0.050*(aeta-1.8)/0.4 /0.05;
    else scale=0.025/0.05;
  */
 
  if (aeta < 1.80)
    scale = 0.;
  else if (aeta < 2.3)
    scale = (0.050 * (aeta - 1.8) / 0.4 + 0.025) / 0.05;
  else
    scale = 0.05 / 0.05;
 
  if (!interpolate) {
    if (particle_type == 0)
      return scale * m_helec[ieta]->GetBinContent(ibinEt + 1);
    else if (particle_type == 1)
      return scale * m_hphot[ieta]->GetBinContent(ibinEt + 1);
    else
      return scale * m_hphot2[ieta]->GetBinContent(
                         ibinEt + 1);  // This is 2, since if particle_type is
                                       // not 0,1,2 we have returned 0 above
  } else {
    if (particle_type == 0)
      return scale * m_helec[ieta]->Interpolate(et);
    else if (particle_type == 1)
      return scale * m_hphot[ieta]->Interpolate(et);
    else
      return scale * m_hphot2[ieta]->Interpolate(
                         et);  // This is 2, since if particle_type is not 0,1,2
                               // we have returned 0
  }
}