/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_5_3_13_patch3/src/HLTrigger/btau/src/HLTDisplacedmumuVtxProducer.cc

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#include <iostream>

#include "FWCore/Framework/interface/ESHandle.h"
#include "FWCore/MessageLogger/interface/MessageLogger.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 "HLTDisplacedmumuVtxProducer.h"

using namespace edm;
using namespace reco;
using namespace std; 
using namespace trigger;
//
// constructors and destructor
//
HLTDisplacedmumuVtxProducer::HLTDisplacedmumuVtxProducer(const edm::ParameterSet& iConfig):     
        src_ (iConfig.getParameter<edm::InputTag>("Src")),
        previousCandTag_(iConfig.getParameter<edm::InputTag>("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()
{

}


// ------------ 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.getByLabel (src_,mucands);
        
        //get the transient track builder:
        edm::ESHandle<TransientTrackBuilder> theB;
        iSetup.get<TransientTrackRecord>().get("TransientTrackBuilder",theB);

        std::auto_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.getByLabel (previousCandTag_,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(vertexCollection);
}



bool HLTDisplacedmumuVtxProducer::checkPreviousCand(const TrackRef& trackref, vector<RecoChargedCandidateRef> & refVect){
  bool ok=false;
  for (unsigned int i=0; i<refVect.size(); i++) {
    if ( refVect[i]->get<TrackRef>() == trackref ) {
      ok=true;
      break;
    }
  }
  return ok;
}