Module to produce the subset of generator particles directly contained in top decay chains. More...

#include <TopQuarkAnalysis/TopEventProducers/interface/TopDecaySubset.h>

Inheritance diagram for TopDecaySubset:

Public Types
enum	FillMode { kStable, kME }
enum	ShowerModel { kStart = -1, kNone, kPythia, kHerwig }
	classification of potential shower types More...
Public Member Functions
virtual void	produce (edm::Event &event, const edm::EventSetup &setup)
	write output into the event
	TopDecaySubset (const edm::ParameterSet &cfg)
	default constructor
	~TopDecaySubset ()
	default destructor
Private Member Functions
void	addDaughters (int &idx, const reco::GenParticle::const_iterator part, reco::GenParticleCollection &target, bool recursive=true)
	recursively fill vector for all further decay particles of a given particle
void	addRadiation (int &idx, const reco::GenParticle::const_iterator part, reco::GenParticleCollection &target)
	fill vector including all radiations from quarks originating from W/top
ShowerModel	checkShowerModel (const std::vector< const reco::GenParticle * > &tops) const
	check the decay chain for the used shower model
void	checkWBosons (std::vector< const reco::GenParticle * > &tops) const
	check whether W bosons are contained in the original gen particle listing
void	clearReferences ()
	clear references
void	fillListing (const std::vector< const reco::GenParticle * > &tops, reco::GenParticleCollection &target)
	fill output vector for full decay chain
void	fillReferences (const reco::GenParticleRefProd &refProd, reco::GenParticleCollection &target)
	fill references for output vector
std::vector< const reco::GenParticle * >	findTops (const reco::GenParticleCollection &parts)
	find top quarks in list of input particles
reco::Particle::LorentzVector	p4 (const std::vector< const reco::GenParticle * >::const_iterator top, int statusFlag)
	calculate lorentz vector from input (dedicated to top reconstruction)
reco::Particle::LorentzVector	p4 (const reco::GenParticle::const_iterator part, int statusFlag)
	calculate lorentz vector from input
Private Attributes
bool	addRadiation_
	add radiation or not?
FillMode	fillMode_
int	motherPartIdx_
std::map< int, std::vector< int > >	refs_
	management of daughter indices for fillRefs
ShowerModel	showerModel_
	parton shower mode (filled in checkShowerModel)
edm::InputTag	src_
	input tag for the genParticle source

Detailed Description

Module to produce the subset of generator particles directly contained in top decay chains.

The module produces the subset of generator particles directly contained in top decay chains. The particles are saved as a collection of reco::GenParticles. Depending on the configuration of the module, the 4-vector kinematics can be taken from the status-3 particles (ME before parton showering) or from the status-2 particles (after parton showering), additionally radiated gluons may be considered during the creation of the subset or not.

Definition at line 27 of file TopDecaySubset.h.

Member Enumeration Documentation

enum TopDecaySubset::FillMode

supported modes to fill the new vectors of gen particles

Enumerator:

kStable
kME

Definition at line 32 of file TopDecaySubset.h.

{kStable, kME};

enum TopDecaySubset::ShowerModel

classification of potential shower types

Enumerator:

kStart
kNone
kPythia
kHerwig

Definition at line 34 of file TopDecaySubset.h.

{kStart=-1, kNone, kPythia, kHerwig};

Constructor & Destructor Documentation

TopDecaySubset::TopDecaySubset ( const edm::ParameterSet & cfg ) [explicit]

default constructor

Definition at line 8 of file TopDecaySubset.cc.

References Exception, fillMode_, edm::ParameterSet::getParameter(), kME, kStable, and mode.

                                                        : 
  src_         (cfg.getParameter<edm::InputTag>("src")),
  addRadiation_(cfg.getParameter<bool>("addRadiation")),
  showerModel_ (kStart)
{
  // mapping of the corresponding fillMode; see FillMode 
  // enumerator of TopDecaySubset for available modes
  std::string mode = cfg.getParameter<std::string>( "fillMode" );
  if(mode=="kME")
    fillMode_=kME;
  else if(mode=="kStable")
    fillMode_=kStable;
  else
    throw cms::Exception("Configuration") << mode << " is not a supported FillMode!\n";

  // produces a set of GenParticles following
  // the decay branch of top quarks to the first level of 
  // stable decay products
  produces<reco::GenParticleCollection>(); 
}

TopDecaySubset::~TopDecaySubset ( )

default destructor

Definition at line 30 of file TopDecaySubset.cc.

{
}

Member Function Documentation

void TopDecaySubset::addDaughters	(	int &	idx,
		const reco::GenParticle::const_iterator	part,
		reco::GenParticleCollection &	target,
		bool	recursive = `true`
	)		`[private]`

recursively fill vector for all further decay particles of a given particle

Definition at line 358 of file TopDecaySubset.cc.

References UserOptions_cff::idx, and refs_.

Referenced by fillListing().

{
  std::vector<int> daughters;
  int idxBuffer = idx;
  for(reco::GenParticle::const_iterator daughter=part->begin(); daughter!=part->end(); ++daughter){
      std::auto_ptr<reco::GenParticle> ptr( new reco::GenParticle( daughter->threeCharge(), daughter->p4(), daughter->vertex(), daughter->pdgId(), daughter->status(), false) );
      target.push_back( *ptr );
      // increment & push index of daughter
      daughters.push_back( ++idx );
      // continue recursively if desired
      if(recursive){
        addDaughters(idx,daughter,target);  
      }
  }  
  if(daughters.size()) {
    refs_[ idxBuffer ] = daughters;
  }
}

void TopDecaySubset::addRadiation	(	int &	idx,
		const reco::GenParticle::const_iterator	part,
		reco::GenParticleCollection &	target
	)		`[private]`

fill vector including all radiations from quarks originating from W/top

Definition at line 337 of file TopDecaySubset.cc.

References UserOptions_cff::idx, refs_, and TopDecayID::stable.

Referenced by fillListing().

{
  std::vector<int> daughters;
  int idxBuffer = idx;
  for(reco::GenParticle::const_iterator daughter=part->begin(); daughter!=part->end(); ++daughter){
    if(daughter->status()<=TopDecayID::stable && daughter->pdgId()!=part->pdgId()){
      // skip comment lines and make sure that
      // the particle is not double counted as 
      // dasughter of itself
      std::auto_ptr<reco::GenParticle> ptr(  new reco::GenParticle( daughter->threeCharge(), daughter->p4(), daughter->vertex(), daughter->pdgId(), daughter->status(), false) );
      target.push_back( *ptr );
      daughters.push_back( ++idx ); //push index of daughter
    }
  }  
  if(daughters.size()) {
    refs_[ idxBuffer ] = daughters;
  }
}

TopDecaySubset::ShowerModel TopDecaySubset::checkShowerModel ( const std::vector< const reco::GenParticle * > & tops ) const [private]

check the decay chain for the used shower model

check the decay chain for the exploited shower model

Definition at line 81 of file TopDecaySubset.cc.

References abs, reco::CompositeRefCandidateT< D >::begin(), reco::CompositeRefCandidateT< D >::end(), Exception, kHerwig, kNone, kPythia, edm::errors::LogicError, reco::CompositeRefCandidateT< D >::numberOfDaughters(), reco::LeafCandidate::pdgId(), TopDecayID::stable, TopDecayID::tID, and TopDecayID::WID.

Referenced by produce().

{
  for(std::vector<const reco::GenParticle*>::const_iterator it=tops.begin(); it!=tops.end(); ++it){
    const reco::GenParticle* top = *it;
    // check for kHerwig type showers: here the status 3 top quark will 
    // have a single status 2 top quark as daughter, which has again 3 
    // or more status 2 daughters
    if( top->numberOfDaughters()==1){
      if( top->begin()->pdgId()==top->pdgId() && top->begin()->status()==TopDecayID::stable && top->begin()->numberOfDaughters()>1)
        return kHerwig;
    }
    // check for kPythia type showers: here the status 3 top quark will 
    // have all decay products and a status 2 top quark as daughters
    // the status 2 top quark will be w/o further daughters
    if( top->numberOfDaughters()>1 ){
      bool containsWBoson=false, containsQuarkDaughter=false;
      for(reco::GenParticle::const_iterator td=top->begin(); td!=top->end(); ++td){
        if( std::abs(td->pdgId ()) <TopDecayID::tID ) containsQuarkDaughter=true;
        if( std::abs(td->pdgId ())==TopDecayID::WID ) containsWBoson=true;
      }
      if(containsQuarkDaughter && containsWBoson)
        return kPythia;
    }
  }
  // if neither Herwig nor Pythia like
  if(tops.size()==0)
    edm::LogWarning("decayChain")
      << " Failed to find top quarks in decay chain. Will assume that this a \n"
      << " non-top sample and produce an empty decaySubset.\n";
  else
    throw edm::Exception(edm::errors::LogicError,
                         " Can not find back any of the supported hadronization models. Models \n"
                         " which are supported are:                                            \n"
                         " Pythia  LO(+PS): Top(status 3) --> WBoson(status 3), Quark(status 3)\n"
                         " Herwig NLO(+PS): Top(status 2) --> Top(status 3) --> Top(status 2)  \n");
  return kNone;
}

void TopDecaySubset::checkWBosons ( std::vector< const reco::GenParticle * > & tops ) const [private]

check whether W bosons are contained in the original gen particle listing

check whether the W boson is contained in the original gen particle listing

Definition at line 121 of file TopDecaySubset.cc.

References abs, reco::CompositeRefCandidateT< D >::begin(), reco::CompositeRefCandidateT< D >::end(), lhef::isContained(), kPythia, edm::errors::LogicError, showerModel_, TopDecayID::stable, TopDecayID::unfrag, and TopDecayID::WID.

Referenced by produce().

{
  unsigned nTops = tops.size();
  for(std::vector<const reco::GenParticle*>::iterator it=tops.begin(); it!=tops.end();) {
    const reco::GenParticle* top = *it;
    bool isContained=false;
    bool expectedStatus=false;
    for(reco::GenParticle::const_iterator td=((showerModel_==kPythia) ? top->begin() : top->begin()->begin());
        td!=((showerModel_==kPythia) ? top->end() : top->begin()->end());
        ++td){
      if(std::abs(td->pdgId())==TopDecayID::WID) {
        isContained=true;
        if( ((showerModel_==kPythia) ? td->status()==TopDecayID::unfrag : td->status()==TopDecayID::stable) ) { 
          expectedStatus=true;
          break;
        }
      }
    }
    if(!expectedStatus) {
      it=tops.erase(it);
      if(isContained)
        edm::LogWarning("decayChain")
          << " W boson does not have the expected status. This happens, e.g.,      \n"
          << " with MC@NLO in the case of additional ttbar pairs from radiated     \n"
          << " gluons. We hope everything is fine, remove the correspdonding top   \n"
          << " quark from our list since it is not part of the primary ttbar pair  \n"
          << " and try to continue.                                                \n";      
    }
    else
      it++;
  }
  if(tops.size()==0 && nTops!=0)
    throw edm::Exception(edm::errors::LogicError,
                         " Did not find a W boson with appropriate status for any of the top   \n"
                         " quarks in this event. This means that the hadronization of the W    \n"
                         " boson might be screwed up or there is another problem with the      \n"
                         " particle listing in this MC sample. Please contact an expert.       \n");
}

void TopDecaySubset::clearReferences ( ) [private]

clear references

Definition at line 379 of file TopDecaySubset.cc.

References motherPartIdx_, and refs_.

Referenced by produce().

{
  // clear vector of references 
  refs_.clear();  
  // set idx for mother particles to a start value
  // of -1 (the first entry will raise it to 0)
  motherPartIdx_=-1;
}

void TopDecaySubset::fillListing	(	const std::vector< const reco::GenParticle * > &	tops,
		reco::GenParticleCollection &	target
	)		`[private]`

fill output vector for full decay chain

Definition at line 162 of file TopDecaySubset.cc.

References abs, addDaughters(), addRadiation(), addRadiation_, reco::CompositeRefCandidateT< D >::begin(), TopDecayID::bID, reco::CompositeRefCandidateT< D >::end(), funct::false, fillMode_, configurableAnalysis::GenParticle, TopDecayID::glueID, kME, kPythia, reco::CompositeRefCandidateT< D >::mother(), motherPartIdx_, reco::CompositeRefCandidateT< D >::numberOfMothers(), p4(), reco::LeafCandidate::pdgId(), refs_, showerModel_, TopDecayID::stable, lumiQTWidget::t, filterCSVwithJSON::target, TopDecayID::tauID, reco::LeafCandidate::threeCharge(), TopDecayID::tID, funct::true, TopDecayID::unfrag, reco::LeafCandidate::vertex(), and TopDecayID::WID.

Referenced by produce().

{
  unsigned int statusFlag;
  // determine status flag of the new 
  // particle depending on the FillMode
  fillMode_ == kME ? statusFlag=3 : statusFlag=2;

  for(std::vector<const reco::GenParticle*>::const_iterator it=tops.begin(); it!=tops.end(); ++it){
    const reco::GenParticle* t = *it;
    // if particle is top or anti-top 
    std::auto_ptr<reco::GenParticle> topPtr( new reco::GenParticle( t->threeCharge(), p4(it, statusFlag), t->vertex(), t->pdgId(), statusFlag, false ) );
    target.push_back( *topPtr );
    ++motherPartIdx_;
    // keep the top index for the map to manage the daughter refs
    int iTop=motherPartIdx_; 
    std::vector<int> topDaughters;
    // define the W boson index (to be set later) for the map to 
    // manage the daughter refs
    int iW = 0;
    std::vector<int> wDaughters;
    //iterate over top daughters
    for(reco::GenParticle::const_iterator td=((showerModel_==kPythia)?t->begin():t->begin()->begin()); td!=((showerModel_==kPythia)?t->end():t->begin()->end()); ++td){
      if( td->status()==TopDecayID::unfrag && std::abs( td->pdgId() )<=TopDecayID::bID ){ 
        // if particle is beauty or other quark 
        std::auto_ptr<reco::GenParticle> bPtr( new reco::GenParticle( td->threeCharge(), p4( td, statusFlag ), td->vertex(), td->pdgId(), statusFlag, false ) );
        target.push_back( *bPtr );        
        // increment & push index of the top daughter
        topDaughters.push_back( ++motherPartIdx_ ); 
        if(addRadiation_){
          addRadiation(motherPartIdx_,td,target); 
        }
      }
      reco::GenParticle::const_iterator buffer = (showerModel_==kPythia)?td:td->begin();
      if( buffer->status()==TopDecayID::unfrag && std::abs( buffer->pdgId() )==TopDecayID::WID ){ 
        // if particle is a W boson
        std::auto_ptr<reco::GenParticle> wPtr(  new reco::GenParticle( buffer->threeCharge(), p4( buffer, statusFlag), buffer->vertex(), buffer->pdgId(), statusFlag, true ) );
        target.push_back( *wPtr );
        // increment & push index of the top daughter
        topDaughters.push_back( ++motherPartIdx_ );
        // keep the W idx for the map
        iW=motherPartIdx_; 
        if(addRadiation_){
          addRadiation(motherPartIdx_,buffer,target); 
        }
        // iterate over W daughters
        for(reco::GenParticle::const_iterator wd=((showerModel_==kPythia)?buffer->begin():buffer->begin()->begin()); wd!=((showerModel_==kPythia)?buffer->end():buffer->begin()->end()); ++wd){
          // make sure the W daughter is of status unfrag and not the W itself
          if( wd->status()==TopDecayID::unfrag && !(std::abs(wd->pdgId())==TopDecayID::WID) ) {
            std::auto_ptr<reco::GenParticle> qPtr( new reco::GenParticle( wd->threeCharge(), p4( wd, statusFlag ), wd->vertex(), wd->pdgId(), statusFlag, false) );
            target.push_back( *qPtr );
            // increment & push index of the top daughter
            wDaughters.push_back( ++motherPartIdx_ );
            if( wd->status()==TopDecayID::unfrag && std::abs( wd->pdgId() )==TopDecayID::tauID ){ 
              // add tau daughters if the particle is a tau pass
              // the daughter of the tau which is of status 2
              //addDaughters(motherPartIdx_, wd->begin(), target); 
              // add tau daughters if the particle is a tau pass
              // the tau itself, which may add a tau daughter of
              // of status 2 to the listing
              addDaughters(motherPartIdx_,wd,target); 
            }
          } 
        }
      }
      if(addRadiation_ && buffer->status()==TopDecayID::stable && ( buffer->pdgId()==TopDecayID::glueID || std::abs(buffer->pdgId())<TopDecayID::bID)){
        // collect additional radiation from the top 
        std::auto_ptr<reco::GenParticle> radPtr( new reco::GenParticle( buffer->threeCharge(), buffer->p4(), buffer->vertex(), buffer->pdgId(), statusFlag, false ) );
        target.push_back( *radPtr );    
        // increment & push index of the top daughter  
        topDaughters.push_back( ++motherPartIdx_ );
      }
    }
    // add potential sisters of the top quark;
    // only for top to prevent double counting
    if(t->numberOfMothers()>0 && t->pdgId()==TopDecayID::tID){
      for(reco::GenParticle::const_iterator ts = t->mother()->begin(); ts!=t->mother()->end(); ++ts){
        // loop over all daughters of the top mother i.e.
        // the two top quarks and their potential sisters
        if(std::abs(ts->pdgId())!=t->pdgId() && ts->pdgId()!=t->mother()->pdgId()){
          // add all further particles but the two top quarks and potential 
          // cases where the mother of the top has itself as daughter
          reco::GenParticle* cand = new reco::GenParticle( ts->threeCharge(), ts->p4(), ts->vertex(), ts->pdgId(), ts->status(), false );
          std::auto_ptr<reco::GenParticle> sPtr( cand );
          target.push_back( *sPtr );
          if(ts->begin()!=ts->end()){ 
            // in case the sister has daughters increment
            // and add the first generation of daughters
            addDaughters(++motherPartIdx_,ts->begin(),target,false);
          }
        }
      }
    }
    // fill the map for the administration 
    // of daughter indices
    refs_[ iTop ] = topDaughters;
    refs_[ iW   ] = wDaughters; 
  }
}

void TopDecaySubset::fillReferences	(	const reco::GenParticleRefProd &	refProd,
		reco::GenParticleCollection &	target
	)		`[private]`

fill references for output vector

Definition at line 390 of file TopDecaySubset.cc.

References reco::CompositeRefCandidateT< D >::addDaughter(), Exception, UserOptions_cff::idx, edm::errors::InvalidReference, AlCaHLTBitMon_ParallelJobs::p, and refs_.

Referenced by produce().

{ 
  int idx=0;
  for(reco::GenParticleCollection::iterator p=sel.begin(); p!=sel.end(); ++p, ++idx){
    //find daughter reference vectors in refs_ and add daughters
    std::map<int, std::vector<int> >::const_iterator daughters=refs_.find( idx );
    if( daughters!=refs_.end() ){
      for(std::vector<int>::const_iterator daughter = daughters->second.begin(); 
          daughter!=daughters->second.end(); ++daughter){
        reco::GenParticle* part = dynamic_cast<reco::GenParticle* > (&(*p));
        if(part == 0){
         throw edm::Exception( edm::errors::InvalidReference, "Not a GenParticle" );
        }
        part->addDaughter( reco::GenParticleRef(ref, *daughter) );
        sel[*daughter].addMother( reco::GenParticleRef(ref, idx) );
      }
    }
  }
}

std::vector< const reco::GenParticle * > TopDecaySubset::findTops ( const reco::GenParticleCollection & parts ) [private]

find top quarks in list of input particles

Definition at line 69 of file TopDecaySubset.cc.

References abs, lumiQTWidget::t, TopDecayID::tID, and TopDecayID::unfrag.

Referenced by produce().

{
  std::vector<const reco::GenParticle*> tops;
  for(reco::GenParticleCollection::const_iterator t=parts.begin(); t!=parts.end(); ++t){
    if( std::abs(t->pdgId())==TopDecayID::tID && t->status()==TopDecayID::unfrag )
      tops.push_back( &(*t) );
  }
  return tops;
}

reco::Particle::LorentzVector TopDecaySubset::p4	(	const std::vector< const reco::GenParticle * >::const_iterator	top,
		int	statusFlag
	)		`[private]`

calculate lorentz vector from input (dedicated to top reconstruction)

calculate lorentz vector from input

Definition at line 263 of file TopDecaySubset.cc.

References abs, AlCaHLTBitMon_ParallelJobs::p, TopDecayID::unfrag, and TopDecayID::WID.

Referenced by fillListing(), and p4().

{
  // calculate the four vector for top/anti-top quarks from 
  // the W boson and the b quark plain or including all 
  // additional radiation depending on switch 'plain'
  if(statusFlag==TopDecayID::unfrag){
    // return 4 momentum as it is
    return (*top)->p4();
  }
  reco::Particle::LorentzVector vec;
  for(reco::GenParticle::const_iterator p=(*top)->begin(); p!=(*top)->end(); ++p){
    if( p->status() == TopDecayID::unfrag ){
      // descend by one level for each
      // status 3 particle on the way
      vec+=p4( p, statusFlag );
    }
    else{ 
      if( std::abs((*top)->pdgId())==TopDecayID::WID ){
        // in case of a W boson skip the status 
        // 2 particle to prevent double counting
        if( std::abs(p->pdgId())!=TopDecayID::WID ) 
          vec+=p->p4();
      } 
      else{
        // add all four vectors for each stable
        // particle (status 1 or 2) on the way 
        vec+=p->p4();
        if( vec.mass()-(*top)->mass()>0 ){
          // continue adding up gluons and qqbar pairs on the top 
          // line untill the nominal top mass is reached; then 
          // break in order to prevent picking up virtualities
          break;
        }
      }
    }
  }
  return vec;
}

reco::Particle::LorentzVector TopDecaySubset::p4	(	const reco::GenParticle::const_iterator	part,
		int	statusFlag
	)		`[private]`

calculate lorentz vector from input

calculate lorentz vector from input (dedicated to top reconstruction)

Definition at line 304 of file TopDecaySubset.cc.

References abs, AlCaHLTBitMon_ParallelJobs::p, p4(), TopDecayID::stable, TopDecayID::unfrag, and TopDecayID::WID.

{
  // calculate the four vector for all top daughters from 
  // their daughters including additional radiation 
  if(statusFlag==TopDecayID::unfrag){
    // return 4 momentum as it is
    return part->p4();
  }
  reco::Particle::LorentzVector vec;
  for(reco::GenParticle::const_iterator p=part->begin(); p!=part->end(); ++p){
    if( p->status()<=TopDecayID::stable && std::abs(p->pdgId ())==TopDecayID::WID){
      vec=p->p4();
    }
    else{
      if(p->status()<=TopDecayID::stable){
        // sum up the p4 of all stable particles 
        // (of status 1 or 2)
        vec+=p->p4();
      }
      else{
        if( p->status()==TopDecayID::unfrag){
          // if the particle is unfragmented (i.e.
          // status 3) descend by one level
          vec+=p4(p, statusFlag);   
        }
      }
    }
  }
  return vec;
}

void TopDecaySubset::produce	(	edm::Event &	event,
		const edm::EventSetup &	setup
	)		`[virtual]`

write output into the event

Implements edm::EDProducer.

Definition at line 36 of file TopDecaySubset.cc.

References checkShowerModel(), checkWBosons(), clearReferences(), fillListing(), fillReferences(), findTops(), kStart, showerModel_, align_tpl::src, src_, and filterCSVwithJSON::target.

{     
  // get source collection
  edm::Handle<reco::GenParticleCollection> src;
  event.getByLabel(src_, src);

  // find top quarks in list of input particles
  std::vector<const reco::GenParticle*> tops = findTops(*src);

  // determine shower model (only in first event)
  if(showerModel_==kStart)
    showerModel_=checkShowerModel(tops);

  // check sanity of W bosons
  checkWBosons(tops);

  // create target vector
  std::auto_ptr<reco::GenParticleCollection> target( new reco::GenParticleCollection );
  // get ref product from the event
  const reco::GenParticleRefProd ref = event.getRefBeforePut<reco::GenParticleCollection>(); 
  // clear existing refs
  clearReferences();  
  // fill output
  fillListing(tops, *target);
  // fill references
  fillReferences(ref, *target);

  // write vectors to the event
  event.put(target);
}