PhysicsAnalysis/TauID/DiTauMassTools/Root/HelperFunctions.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
// vim: ts=2 sw=2
 
// if included, do not use fast calculation of sin/cos but built-in functions
//#define NOFASTSINCOS
 
// local include(s)
#include "DiTauMassTools/HelperFunctions.h"
#include "xAODBase/IParticle.h"
#include "xAODBase/ObjectType.h"
#include "xAODTau/TauJet.h"
 
#include <TKey.h>
#include <TCollection.h> // for TIter
#include <TDirectory.h>
#include <TF1.h>
#include <TROOT.h> //for gROOT
 
using namespace DiTauMassTools;
 
double DiTauMassTools::MaxDelPhi(int tau_type, double Pvis, double dRmax_tau)
{
  return dRmax_tau+0*Pvis*tau_type; // hack to avoid warning
}
 
//put back phi within -pi, +pi
double DiTauMassTools::fixPhiRange  (const double & phi)
{
  double phiOut=phi;
 
  if (phiOut>0){
    while (phiOut>TMath::Pi()) {
      phiOut-=TMath::TwoPi();
    }
  }
 
  else{
    while (phiOut<-TMath::Pi()) {
      phiOut+=TMath::TwoPi();
    }
  }
  return phiOut;
}
 
// fast approximate calculation of sin and cos
// approximation good to 1 per mill. c^2+s^2=1 strictly exact though
// it is like using slightly different values of phi1 and phi2
void DiTauMassTools::fastSinCos (const double & phiInput, double & sinPhi, double & cosPhi)
{
  const double fastB=4/TMath::Pi();
  const double fastC=-4/(TMath::Pi()*TMath::Pi());
  const double fastP=9./40.;
  const double fastQ=31./40.;
  // use normal sin cos if switch off
#ifdef NOFASTSINCOS
  sinPhi=sin(phiInput);
  cosPhi=cos(phiInput);
#else
 
 
  double phi = fixPhiRange(phiInput);
 
  // http://devmaster.net/forums/topic/4648-fast-and-accurate-sinecosine/
  // accurate to 1 per mille
 
  // even faster
  //  const double y=fastB*phi+fastC*phi*std::abs(phi);
  // sinPhi=fastP*(y*std::abs(y)-y)+y;
  const double y=phi*(fastB+fastC*std::abs(phi));
  sinPhi=y*(fastP*std::abs(y)+fastQ);
 
 
  //note that one could use cos(phi)=sin(phi+pi/2), however then one would not have c^2+s^2=1 (would get it only within 1 per mille)
  // the choice here is to keep c^2+s^2=1 so everything is as one would compute c and s from a slightly (1 per mille) different angle
  cosPhi=sqrt(1-std::pow(sinPhi,2));
  if (std::abs(phi)>TMath::PiOver2()) cosPhi=-cosPhi;
#endif
}
 
// return true if cache was uptodate
bool DiTauMassTools::updateDouble  (const double in, double & out)
{
  if (out==in) return true;
  out=in;
  return false;
}
 
//CP::CorrectionCode MissingMassTool::getLFVMode( const xAOD::IParticle* p1, const xAOD::IParticle* p2, int mmcType1, int mmcType2) {
int DiTauMassTools::getLFVMode( const xAOD::IParticle* p1, const xAOD::IParticle* p2, int mmcType1, int mmcType2) {
 
  // Check if particles pointers are null
  if(p1 == nullptr || p2 == nullptr) {
      Info("DiTauMassTools", "MissingMassTool::getLFVMode() got a nullptr - returning -1");
      return -1;
  }
 
  // In case we're in LFV calibration, pass the LFV mode to the tool
  if (mmcType1 == -1) mmcType1 = mmcType(p1);
  if (mmcType1 < 0) return -1;//return CP::CorrectionCode::Error;
 
  if (mmcType2 == -1) mmcType2 = mmcType(p2);
  if (mmcType2 < 0) return -1;//return CP::CorrectionCode::Error;
 
  // we don't use mmcType as it's 0 for both leptons
  const xAOD::IParticle *p;
  if(mmcType1 == 8 && mmcType2 == 8) {
    // both leptonic; find whichever has the highest pT
    if(p1->pt() > p2->pt() ) {
      p = p1;
    } else {
      p = p2;
    }
 
  } else {
    // one of them is a lepton, find it
    if(mmcType1 == 8) {
      p = p1;
    } else if(mmcType2 == 8) {
      p = p2;
    } else {
      // if you're here, you've passed 2 taus to the LFV mode.
      Warning("DiTauMassTools", "Trying to set LFV mode for 2 taus!");
      return -1;//return CP::CorrectionCode::Error;
    }
  }
 
 
  int LFVMode = -1;
  if(p->type() == xAOD::Type::Muon) {
    // mu+tau mode
    LFVMode = 1;
  } else {
    // e+tau mode
    LFVMode = 0;
  }
 
  return LFVMode;
  //return CP::CorrectionCode::Ok;
}
 
int DiTauMassTools::mmcType(const xAOD::IParticle* part)
{
  if(part == nullptr) {
    // idea for fix: pass logger object to this function or whole algorithm that inherited from athena as pointer
    Info("DiTauMassTools", "MissingMassTool::mmcType() got a nullptr - returning -1");
    return -1;
  }
 
  xAOD::Type::ObjectType partType=part->type();
  int aType=-1;
  if (partType==xAOD::Type::Electron || partType==xAOD::Type::Muon)
  {
    aType=8; // PanTau_DecayMode for leptonic taus
  }
  else if (partType==xAOD::Type::Tau)
  {
    const xAOD::TauJet * aTauJet=dynamic_cast<const xAOD::TauJet*>(part);
    if (aTauJet==0)
    {
      Warning("DiTauMassTools", "MissingMassTool::mmcType() dynamic_cast of TauJet failed");
      aType=-2;
    }
    else
    {
      aTauJet->panTauDetail(xAOD::TauJetParameters::PanTau_DecayMode, aType); // 0: 1p0n, 1: 1p1n, 2: 1pXn, 3: 3p0n, 4: 3pXn, 5: Other (2p, 4p, 5p), 6: not set (0p, >=6p), 7: error, 8: leptonic
    }
  }
  else
  {
    Warning("DiTauMassTools", "MissingMassTool::mmcType() unrecognised particle type! Only Electron, Muon, TauJet allowed. If no mistake, please call MissingMassTool::calculate() directly.");
    aType=-1;
  }
 
  return aType;
}
//________________________________________________________________________
 
void DiTauMassTools::readInParams(TDirectory* dir, MMCCalibrationSet::e aset, std::vector<TF1*>& lep_numass, std::vector<TF1*>& lep_angle, std::vector<TF1*>& lep_ratio, std::vector<TF1*>& had_angle, std::vector<TF1*>& had_ratio) {
    std::string paramcode;
    if (aset == MMCCalibrationSet::MMC2019) paramcode = "MMC2019MC16";
    else if (aset == MMCCalibrationSet::MMC2024) paramcode = "MMC2024MC23";
    else {
        Info("DiTauMassTools", "The specified calibration version does not support root file parametrisations");
        return;
    }
    TIter next(dir->GetListOfKeys());
    TKey* key;
    while ((key = (TKey*)next())) {
        TClass *cl = gROOT->GetClass(key->GetClassName());
        // if there is another subdirectory, go into that dir
        if (cl->InheritsFrom("TDirectory")) {
            dir->cd(key->GetName());
            TDirectory *subdir = gDirectory;
            readInParams(subdir, aset, lep_numass, lep_angle, lep_ratio, had_angle, had_ratio);
            dir->cd();
        }
        else if (cl->InheritsFrom("TF1") || cl->InheritsFrom("TGraph")) {
            // get parametrisations and sort them into their corresponding vectors
            std::string total_path = dir->GetPath();
            if (total_path.find(paramcode) == std::string::npos) continue;
            TF1* func = (TF1*)dir->Get( (const char*) key->GetName() );
            TF1* f = new TF1(*func);
            if (total_path.find("lep") != std::string::npos)
            {
                if (total_path.find("Angle") != std::string::npos){
                    lep_angle.push_back(f);
                }
                else if (total_path.find("Ratio") != std::string::npos)
                {
                    lep_ratio.push_back(f);
                }
                else if (total_path.find("Mass") != std::string::npos)
                {
                    lep_numass.push_back(f);
                }
                else
                {
                    Warning("DiTauMassTools", "Undefined leptonic PDF term in input file.");
                }
            }
            else if (total_path.find("had") != std::string::npos)
            {
                if (total_path.find("Angle") != std::string::npos){
                    had_angle.push_back(f);
                }
                else if (total_path.find("Ratio") != std::string::npos)
                {
                    had_ratio.push_back(f);
                }
                else
                {
                    Warning("DiTauMassTools", "Undefined hadronic PDF term in input file.");
                }
            }
            else
            {
                Warning("DiTauMassTools", "Undefined decay channel in input file.");
            }
        }
        else {
            Warning("DiTauMassTools", "Class in input file not recognized.");
        }
    }
}