HLTDisplacedmumuVtxProducer.cc

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#include <iostream>

#include "FWCore/Framework/interface/ESHandle.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"

#include "DataFormats/Candidate/interface/CandidateFwd.h"
#include "DataFormats/RecoCandidate/interface/RecoCandidate.h"
#include "DataFormats/RecoCandidate/interface/RecoChargedCandidate.h"
#include "DataFormats/RecoCandidate/interface/RecoChargedCandidateFwd.h"
#include "DataFormats/Candidate/interface/Candidate.h"
#include "DataFormats/HLTReco/interface/TriggerFilterObjectWithRefs.h"
#include "DataFormats/HLTReco/interface/TriggerRefsCollections.h"

#include "DataFormats/TrackReco/interface/TrackFwd.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "TrackingTools/TransientTrack/interface/TransientTrackBuilder.h"
#include "TrackingTools/Records/interface/TransientTrackRecord.h"

#include "RecoVertex/KalmanVertexFit/interface/KalmanVertexFitter.h"
#include "RecoVertex/VertexPrimitives/interface/TransientVertex.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/Common/interface/RefToBase.h"


#include "HLTrigger/btau/src/HLTDisplacedmumuVtxProducer.h"

using namespace edm;
using namespace reco;
using namespace std; 
using namespace trigger;
//
// constructors and destructor
//
HLTDisplacedmumuVtxProducer::HLTDisplacedmumuVtxProducer(const edm::ParameterSet& iConfig): 
    srcTag_ (iConfig.getParameter<edm::InputTag>("Src")),
    srcToken_(consumes<reco::RecoChargedCandidateCollection>(srcTag_)),
        previousCandTag_(iConfig.getParameter<edm::InputTag>("PreviousCandTag")),
    previousCandToken_(consumes<trigger::TriggerFilterObjectWithRefs>(previousCandTag_)),
    maxEta_ (iConfig.getParameter<double>("MaxEta")),
    minPt_ (iConfig.getParameter<double>("MinPt")),
    minPtPair_ (iConfig.getParameter<double>("MinPtPair")),
    minInvMass_ (iConfig.getParameter<double>("MinInvMass")),
    maxInvMass_ (iConfig.getParameter<double>("MaxInvMass")),
    chargeOpt_ (iConfig.getParameter<int>("ChargeOpt"))
{
    produces<VertexCollection>();
}


HLTDisplacedmumuVtxProducer::~HLTDisplacedmumuVtxProducer() = default;

void
HLTDisplacedmumuVtxProducer::fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
  edm::ParameterSetDescription desc;
  desc.add<edm::InputTag>("Src",edm::InputTag("hltL3MuonCandidates"));
  desc.add<edm::InputTag>("PreviousCandTag",edm::InputTag(""));
  desc.add<double>("MaxEta",2.5);
  desc.add<double>("MinPt",0.0);
  desc.add<double>("MinPtPair",0.0);
  desc.add<double>("MinInvMass",1.0);
  desc.add<double>("MaxInvMass",20.0);
  desc.add<int>("ChargeOpt",-1);
  descriptions.add("hltDisplacedmumuVtxProducer", desc);
}

// ------------ method called once each job just before starting event loop  ------------
void HLTDisplacedmumuVtxProducer::beginJob()
{

}

// ------------ method called once each job just after ending the event loop  ------------
void HLTDisplacedmumuVtxProducer::endJob() 
{
    
}

// ------------ method called on each new Event  ------------
void HLTDisplacedmumuVtxProducer::produce(edm::Event& iEvent, const edm::EventSetup& iSetup)
{
    double const MuMass = 0.106;
    double const MuMass2 = MuMass*MuMass;
    
    
    // get hold of muon trks
    Handle<RecoChargedCandidateCollection> mucands;
    iEvent.getByToken(srcToken_,mucands);
    
    //get the transient track builder:
    edm::ESHandle<TransientTrackBuilder> theB;
    iSetup.get<TransientTrackRecord>().get("TransientTrackBuilder",theB);

    std::unique_ptr<VertexCollection> vertexCollection(new VertexCollection());

    // look at all mucands,  check cuts and make vertices
    double e1,e2;
    Particle::LorentzVector p,p1,p2;
    
    RecoChargedCandidateCollection::const_iterator cand1;
    RecoChargedCandidateCollection::const_iterator cand2;
    
    // get the objects passing the previous filter
    Handle<TriggerFilterObjectWithRefs> previousCands;
    iEvent.getByToken(previousCandToken_,previousCands);

    vector<RecoChargedCandidateRef> vPrevCands;
    previousCands->getObjects(TriggerMuon,vPrevCands);

    for (cand1=mucands->begin(); cand1!=mucands->end(); cand1++) {
           TrackRef tk1 = cand1->get<TrackRef>();
           LogDebug("HLTDisplacedMumuFilter") << " 1st muon in loop: q*pt= " << cand1->charge()*cand1->pt() << ", eta= " << cand1->eta() << ", hits= " << tk1->numberOfValidHits();
         
           //first check if this muon passed the previous filter
           if( ! checkPreviousCand( tk1, vPrevCands) ) continue;
    
           // cuts
           if (fabs(cand1->eta())>maxEta_) continue;
           if (cand1->pt() < minPt_) continue;
          
           cand2 = cand1; cand2++;
           for (; cand2!=mucands->end(); cand2++) {
                 TrackRef tk2 = cand2->get<TrackRef>();
         
             // eta cut
             LogDebug("HLTDisplacedmumuVtxProducer") << " 2nd muon in loop: q*pt= " << cand2->charge()*cand2->pt() << ", eta= " << cand2->eta() << ", hits= " << tk2->numberOfValidHits() << ", d0= " << tk2->d0();
             //first check if this muon passed the previous filter
             if( ! checkPreviousCand( tk2, vPrevCands) ) continue;
             
             // cuts
             if (fabs(cand2->eta())>maxEta_) continue;
             if (cand2->pt() < minPt_) continue;
             
             // opposite sign or same sign
             if (chargeOpt_<0) {
               if (cand1->charge()*cand2->charge()>0) continue;
             } else if (chargeOpt_>0) {
               if (cand1->charge()*cand2->charge()<0) continue;
             }
             
             // Combined dimuon system
             e1 = sqrt(cand1->momentum().Mag2()+MuMass2);
             e2 = sqrt(cand2->momentum().Mag2()+MuMass2);
             p1 = Particle::LorentzVector(cand1->px(),cand1->py(),cand1->pz(),e1);
             p2 = Particle::LorentzVector(cand2->px(),cand2->py(),cand2->pz(),e2);
             p = p1+p2;
             
             
             if (p.pt()<minPtPair_) continue;
             
             double invmass = abs(p.mass());
             LogDebug("HLTDisplacedMumuFilter") << " ... 1-2 invmass= " << invmass;
             
             if (invmass<minInvMass_) continue;
             if (invmass>maxInvMass_) continue;
             
             // do the vertex fit
             vector<TransientTrack> t_tks;
             TransientTrack ttkp1 = (*theB).build(&tk1);
             TransientTrack ttkp2 = (*theB).build(&tk2);
             t_tks.push_back(ttkp1);
             t_tks.push_back(ttkp2);
             
        
             if (t_tks.size()!=2) continue;
            
             KalmanVertexFitter kvf;
             TransientVertex tv = kvf.vertex(t_tks);

             if (!tv.isValid()) continue;
             
             Vertex vertex = tv;

             // put vertex in the event
             vertexCollection->push_back(vertex);
           }
    }
    iEvent.put(std::move(vertexCollection));
}



bool HLTDisplacedmumuVtxProducer::checkPreviousCand(const TrackRef& trackref, vector<RecoChargedCandidateRef> & refVect){
  bool ok=false;
  for (auto & i : refVect) {
    if ( i->get<TrackRef>() == trackref ) {
      ok=true;
      break;
    }
  }
  return ok;
}