TruthTools.h

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/*
   Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
// Filename: TruthTools.h
// Description:
// Author: Fabian Wilk
// Created: Wed Feb  4 11:04:23 2015
 
#ifndef _TOP_PARTICLE_LEVEL_TRUTHTOOLS_H_
#define _TOP_PARTICLE_LEVEL_TRUTHTOOLS_H_
 
#include <ostream>
#include <iostream>
#include <string>
 
#include "xAODTruth/TruthParticleContainer.h"
#include "xAODMuon/MuonContainer.h"
#include "TopEvent/EventTools.h"
#include "TopDataPreparation/SampleXsection.h"
#include "xAODBase/IParticle.h"
 
namespace top {
  namespace truth {
    //Functions to decorate a muon with information on its truth-origin. Particle-level origin added on softmuons if config options SoftMuonAdditionalTruthInfo is True.
    //Its output should be regarded as experimental and thoroughly tested by analyzers before officially including it in the analysis.
    //It is strongly suggested to check its output against the true_origin (calculated by the MCTruthClassifier) to ensure behaviour is as expected.
    //Parton-level added if SoftMuonAdditionalTruthInfo is True and SoftMuonAdditionalTruthInfoCheckPartonOrigin is True.
    //Parton-level currently only usable on pythia8 and herwig7, will be automatically disabled for other PS generators.
    //Some decorations are already written in the default output ntuple, check EventSaverFlatNtuple.cxx
    //Some other are available for usage in custom savers:
    //<const xAOD::TruthParticle*>("truthMuonLink") -> link to the truth muon associated with reco (can be null if not found)
    //<top::LepParticleOriginFlag>("LepParticleOriginFlag") -> flag defined in TopEvent/EventTools.h
    //<top::LepPartonOriginFlag>("LepPartonOriginFlag") -> flag defined in TopEvent/EventTools.h
    //Then several <const xAOD::TruthParticle*>(...) decorations are also added (pointers are 0 when corresponding particle is not available):
    //truthMotherLink -> first direct mother of the truth muon
    //truthFirstNonLeptonMotherLink -> self-explanatory, will be different from truthMotherLink if the muon is from a Tau
    //truthBMotherLink -> first B-hadron encountered when going back through the chain of ancestors
    //truthCMotherLink -> first C-hadron encountered when going back through the chain of ancestors
    //The following are added when using the parton-level flag
    //truthPartonMotherLink -> link to first b/c quark encountered when going back through the chain of ancestors for muons from Heavy Flavour hadrons decays
    //truthTopMotherLink, truthWMotherLink, truthZMotherLink, truthPhotonMotherLink, truthHiggsMotherLink, truthBSMMotherLink -> link to first Top/W/Z/gamma*/Higgs/BSM-particle encountered when going back through the chain of ancestors
 
    void getTruthMuonHistory(const xAOD::TruthParticle* truth_muon, bool doPartonHistory, SampleXsection::showering shAlgo, bool verbose=false);
    void getTruthMuonPartonHistory(const xAOD::TruthParticle* truthmu, top::LepParticleOriginFlag lepParticleOriginFlag, const xAOD::TruthParticle* truthmu_Bmother, const xAOD::TruthParticle* truthmu_Cmother,  const xAOD::TruthParticle* truthmu_firstNonLeptonMother, SampleXsection::showering shAlgo, bool verbose=false);
    //helper methods
    top::LepParticleOriginFlag getTruthMuonFromTauHistory(const xAOD::TruthParticle* tauMother, const xAOD::TruthParticle* &truthmu_Bmother, const xAOD::TruthParticle* &truthmu_Cmother, const xAOD::TruthParticle* &truthmu_firstNonLeptonMother, bool verbose=false);
    top::LepParticleOriginFlag getTruthMuonFromCharmHistory(const xAOD::TruthParticle* &truthmu_Bmother, const xAOD::TruthParticle* truthmu_Cmother, bool verbose=false);
    
    //function that gets the truth muon associated from a reco muon, runs getTruthMuonHistory on it, and then takes care of propagating the decorations
    void getRecoMuonHistory(const xAOD::Muon* muon, bool doPartonHistory, SampleXsection::showering shAlgo, bool verbose=false);
    
    //helper methods
    const xAOD::TruthParticle* getInitialStateParticle(const xAOD::TruthParticle* truthParticle, bool verbose=false);
    const xAOD::TruthParticle* getFirstHFHadronOfSameFlavour(const xAOD::TruthParticle* truthParticle, bool verbose=false);
    const xAOD::TruthParticle* getTruthMuonAssociatedToRecoMuon(const xAOD::Muon* muon);
    //to initialize correctly all decorations to default values
    void initTruthMuonHistoryInfo(const xAOD::TruthParticle* truth_muon, bool doPartonHistory);
    void initRecoMuonHistoryInfo(const xAOD::Muon* muon, bool doPartonHistory);
    //additional method to share common code between the two methods above
    void initCommonMuonHistoryInfo(const xAOD::IParticle* muon, bool doPartonHistory);
    //helper methods to copy info from one muon to another
    void copyTruthMuonHistoryInfo(const xAOD::TruthParticle* tm_origin, const xAOD::TruthParticle* tm_target);
    void copyRecoMuonHistoryInfo(const xAOD::Muon* m_origin, const xAOD::Muon* m_target);
    //additional method to share common code between the two methods above
    void copyCommonMuonHistoryInfo(const xAOD::IParticle*  m_origin, const xAOD::IParticle* m_target);
    
    void printDecayChain(const xAOD::TruthParticle* part,
                         std::ostream& os = std::cout,
                         const std::string& prefix = "");
 
    inline bool isBHadron(int pdgId) {
      return((510 < pdgId && pdgId < 555) ||  // Check for (normal) Mesons / Diquarks
             (5100 < pdgId && pdgId < 5555) ||// Check for (normal) Baryons
             (pdgId / 100) % 10 == 5 ||   // Check exited Mesons (and Baryons with double beauty)
             (pdgId / 1000) % 10 == 5);   // Check exited Baryons
    }
 
    bool isFrom(const xAOD::TruthParticle* truthParticle,
                const std::vector<int>& parentPDGIds,
                bool bOnlyDirect = false);
 
    bool isFromWZDecay(const xAOD::TruthParticle* truthParticle,
                       bool bOnlyDirect = false);
 
    bool isLeptonFromTau(const xAOD::TruthParticle* truthParticle);
 
    inline bool isLepton(const xAOD::TruthParticle* truthParticle) {
      return(10 < truthParticle->absPdgId() && truthParticle->absPdgId() < 17);
    }
 
    bool isNotFromHadron(const xAOD::TruthParticle* truthParticle,
                         bool bOnlyDirect = false, bool bTauIsHadron = false);
  }
}
 
#endif /* _TOP_PARTICLE_LEVEL_TRUTHTOOLS_H_ */