---

KineExample.cc

Go to the documentation of this file.

#include "RecoVertex/KinematicFit/plugins/KineExample.h"

#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/TrackReco/interface/TrackFwd.h"
#include "DataFormats/Common/interface/EDProduct.h"
#include "DataFormats/Common/interface/Handle.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Framework/interface/ESHandle.h"

#include "TrackingTools/TransientTrack/interface/TransientTrackBuilder.h"
#include "TrackingTools/Records/interface/TransientTrackRecord.h"
#include "TrackingTools/TransientTrack/interface/TransientTrack.h"
#include "RecoVertex/VertexPrimitives/interface/TransientVertex.h"
#include "RecoVertex/KalmanVertexFit/interface/KalmanVertexFitter.h"
#include "SimTracker/Records/interface/TrackAssociatorRecord.h"

#include "RecoVertex/KinematicFitPrimitives/interface/ParticleMass.h"
#include "RecoVertex/KinematicFitPrimitives/interface/MultiTrackKinematicConstraint.h"
#include <RecoVertex/KinematicFitPrimitives/interface/KinematicParticleFactoryFromTransientTrack.h>
// #include "RecoVertex/KinematicFitPrimitives/interface/"
#include "RecoVertex/KinematicFit/interface/KinematicConstrainedVertexFitter.h"
#include "RecoVertex/KinematicFit/interface/TwoTrackMassKinematicConstraint.h"
#include "RecoVertex/KinematicFit/interface/KinematicParticleVertexFitter.h"
#include "RecoVertex/KinematicFit/interface/KinematicParticleFitter.h"
#include "RecoVertex/KinematicFit/interface/MassKinematicConstraint.h"

#include <iostream>

using namespace reco;
using namespace edm;
using namespace std;

KineExample::KineExample(const edm::ParameterSet& iConfig)
  : theConfig(iConfig)
{
  trackLabel_ = iConfig.getParameter<std::string>("TrackLabel");
  outputFile_ = iConfig.getUntrackedParameter<std::string>("outputFile");
  kvfPSet = iConfig.getParameter<edm::ParameterSet>("KVFParameters");
//   rootFile_ = TFile::Open(outputFile_.c_str(),"RECREATE");
  edm::LogInfo("RecoVertex/KineExample")
    << "Initializing KVF TEST analyser  - Output file: " << outputFile_ <<"\n";
}


KineExample::~KineExample() {
//   delete rootFile_;
}

void KineExample::beginJob(edm::EventSetup const& setup){
  edm::ESHandle<TrackAssociatorBase> theAssociatorForParamAtPca;
  setup.get<TrackAssociatorRecord>().get("TrackAssociatorByChi2",theAssociatorForParamAtPca);
  associatorForParamAtPca = (TrackAssociatorByChi2 *) theAssociatorForParamAtPca.product();

//   tree = new SimpleVertexTree("VertexFitter", associatorForParamAtPca);
}


void KineExample::endJob() {
//   delete tree;
}

//
// member functions
//

void
KineExample::analyze(const edm::Event& iEvent, const edm::EventSetup& iSetup)
{

  edm::LogInfo("RecoVertex/KineExample")
    << "Reconstructing event number: " << iEvent.id() << "\n";
  
  // get RECO tracks from the event
  // `tks` can be used as a ptr to a reco::TrackCollection
  edm::Handle<reco::TrackCollection> tks;
  iEvent.getByLabel(trackLabel_, tks);
  if (!tks.isValid()) {
    cout
      << "Exception during event number: " << iEvent.id()
      << "\n";
  } else {

    edm::LogInfo("RecoVertex/KineExample")
      << "Found: " << (*tks).size() << " reconstructed tracks" << "\n";
    cout << "got " << (*tks).size() << " tracks " << endl;
    
    // Transform Track to TransientTrack
    
    //get the builder:
    edm::ESHandle<TransientTrackBuilder> theB;
    iSetup.get<TransientTrackRecord>().get("TransientTrackBuilder",theB);
    //do the conversion:
    vector<TransientTrack> t_tks = (*theB).build(tks);
    
    edm::LogInfo("RecoVertex/KineExample")
      << "Found: " << t_tks.size() << " reconstructed tracks" << "\n";
    
    // Do a KindFit, if >= 4 tracks.
    if (t_tks.size() > 3) {
      
      // For a first test, suppose that the first four tracks are the 2 muons,
      // then the 2 kaons. Since this will not be true, the result of the fit
      // will not be meaningfull, but at least you will get the idea of how to
      // do such a fit.
      
      //First, to get started, a simple vertex fit:
      
      vector<TransientTrack> ttv;  
      ttv.push_back(t_tks[0]); ttv.push_back(t_tks[1]); ttv.push_back(t_tks[2]);ttv.push_back(t_tks[3]);
      KalmanVertexFitter kvf(false);
      TransientVertex tv = kvf.vertex(ttv);
      
      std::cout << "Position: " << Vertex::Point(tv.position()) << "\n";
      
      
      TransientTrack ttMuPlus = t_tks[0];
      TransientTrack ttMuMinus = t_tks[1];
      TransientTrack ttKPlus = t_tks[2];
      TransientTrack ttKMinus = t_tks[3];
      
      //the final state muons and kaons from the Bs->J/PsiPhi->mumuKK decay
      //Creating a KinematicParticleFactory
      KinematicParticleFactoryFromTransientTrack pFactory;
      
      //The mass of a muon and the insignificant mass sigma to avoid singularities in the covariance matrix.
      ParticleMass muon_mass = 0.1056583;
      ParticleMass kaon_mass = 0.493677;
      float muon_sigma = 0.0000000001;
      float kaon_sigma = 0.000016;
      
      //initial chi2 and ndf before kinematic fits. The chi2 of the reconstruction is not considered
      float chi = 0.;
      float ndf = 0.;
      
      //making particles
      vector<RefCountedKinematicParticle> muonParticles;
      vector<RefCountedKinematicParticle> phiParticles;
      vector<RefCountedKinematicParticle> allParticles;
      muonParticles.push_back(pFactory.particle (ttMuPlus,muon_mass,chi,ndf,muon_sigma));
      muonParticles.push_back(pFactory.particle (ttMuMinus,muon_mass,chi,ndf,muon_sigma));
      allParticles.push_back(pFactory.particle (ttMuPlus,muon_mass,chi,ndf,muon_sigma));
      allParticles.push_back(pFactory.particle (ttMuMinus,muon_mass,chi,ndf,muon_sigma));
      
      phiParticles.push_back(pFactory.particle (ttKPlus,kaon_mass,chi,ndf,kaon_sigma));
      phiParticles.push_back(pFactory.particle (ttKMinus,kaon_mass,chi,ndf,kaon_sigma));
      allParticles.push_back(pFactory.particle (ttKPlus,kaon_mass,chi,ndf,kaon_sigma));
      allParticles.push_back(pFactory.particle (ttKMinus,kaon_mass,chi,ndf,kaon_sigma));
      
      /* Example of a simple vertex fit, without other constraints
       * The reconstructed decay tree is a result of the kinematic fit
       * The KinematicParticleVertexFitter fits the final state particles to their vertex and
       * reconstructs the decayed state
       */
      KinematicParticleVertexFitter fitter;
      RefCountedKinematicTree vertexFitTree = fitter.fit(allParticles);
      
      printout(vertexFitTree);
      
        
        //creating the constraint for the J/Psi mass
        ParticleMass jpsi = 3.09687;
        
        //creating the two track mass constraint
        MultiTrackKinematicConstraint *  j_psi_c = new  TwoTrackMassKinematicConstraint(jpsi);
        
        //creating the fitter
        KinematicConstrainedVertexFitter kcvFitter;
        
        //obtaining the resulting tree
        RefCountedKinematicTree myTree = kcvFitter.fit(allParticles, j_psi_c);
        
        cout << "Global fit done:\n";
        printout(myTree);
        
        //creating the vertex fitter
        KinematicParticleVertexFitter kpvFitter;
        
        //reconstructing a J/Psi decay
        RefCountedKinematicTree jpTree = kpvFitter.fit(muonParticles);
        
        //creating the particle fitter
        KinematicParticleFitter csFitter;
        
        // creating the constraint
        float jp_m_sigma = 0.00004;
        KinematicConstraint * jpsi_c2 = new MassKinematicConstraint(jpsi,jp_m_sigma);
        
        //the constrained fit:  
        jpTree = csFitter.fit(jpsi_c2,jpTree);
        
        //getting the J/Psi KinematicParticle and putting it together with the kaons.
        //The J/Psi KinematicParticle has a pointer to the tree it belongs to  
        jpTree->movePointerToTheTop();
        RefCountedKinematicParticle jpsi_part = jpTree->currentParticle();
        phiParticles.push_back(jpsi_part);
        
        //making a vertex fit and thus reconstructing the Bs parameters  
        // the resulting tree includes all the final state tracks, the J/Psi meson,
        // its decay vertex, the Bs meson and its decay vertex.
        RefCountedKinematicTree bsTree = kpvFitter.fit(phiParticles); 
        cout << "Sequential fit done:\n";
        printout(bsTree);
        
        
        
//       // For the analysis: compare to your SimVertex
//       TrackingVertex sv = getSimVertex(iEvent);
//   edm::Handle<TrackingParticleCollection>  TPCollectionH ;
//   iEvent.getByLabel("trackingtruth","TrackTruth",TPCollectionH);
//   const TrackingParticleCollection tPC = *(TPCollectionH.product());
//       reco::RecoToSimCollection recSimColl=associatorForParamAtPca->associateRecoToSim(tks,
//                                                                            TPCollectionH,
//                                                                            &iEvent);
// 
//       tree->fill(tv, &sv, &recSimColl);
//     }

    }
  }  
}

void KineExample::printout(const RefCountedKinematicVertex& myVertex) const
{
  cout << "Decay vertex: " << myVertex->position() <<endl;
}

void KineExample::printout(const RefCountedKinematicParticle& myParticle) const
{
  cout << "Particle: \n";
//accessing the reconstructed Bs meson parameters:
  AlgebraicVector7 bs_par = myParticle->currentState().kinematicParameters().vector();

//and their joint covariance matrix:
  AlgebraicSymMatrix77 bs_er = myParticle->currentState().kinematicParametersError().matrix();
  cout << "Momentum at vertex: " << myParticle->currentState().globalMomentum ()<<endl;
  cout << "Parameters at vertex: " << myParticle->currentState().kinematicParameters().vector()<<endl;
}

void KineExample::printout(const RefCountedKinematicTree& myTree) const
{

//accessing the tree components, move pointer to top
  myTree->movePointerToTheTop();

//We are now at the top of the decay tree getting the B_s reconstructed KinematicPartlcle
  RefCountedKinematicParticle b_s = myTree->currentParticle();
  printout(b_s);

// The B_s decay vertex
  RefCountedKinematicVertex b_dec_vertex = myTree->currentDecayVertex();
  printout(b_dec_vertex);

  // Get all the children of Bs:
  //In this way, the pointer is not moved
  vector< RefCountedKinematicParticle > bs_children = myTree->finalStateParticles();

  for (unsigned int i=0;i< bs_children.size();++i) {
    printout(bs_children[i]);
  }

//Now navigating down the tree , pointer is moved:
  bool child = myTree->movePointerToTheFirstChild();

  if(child) while (myTree->movePointerToTheNextChild()) {
    RefCountedKinematicParticle aChild = myTree->currentParticle();
    printout(aChild);
  }
}

//Returns the first vertex in the list.

TrackingVertex KineExample::getSimVertex(const edm::Event& iEvent) const
{
   // get the simulated vertices
  edm::Handle<TrackingVertexCollection>  TVCollectionH ;
  iEvent.getByLabel("trackingtruth","VertexTruth",TVCollectionH);
  const TrackingVertexCollection tPC = *(TVCollectionH.product());

//    Handle<edm::SimVertexContainer> simVtcs;
//    iEvent.getByLabel("g4SimHits", simVtcs);
//    std::cout << "SimVertex " << simVtcs->size() << std::endl;
//    for(edm::SimVertexContainer::const_iterator v=simVtcs->begin();
//        v!=simVtcs->end(); ++v){
//      std::cout << "simvtx "
//             << v->position().x() << " "
//             << v->position().y() << " "
//             << v->position().z() << " "
//             << v->parentIndex() << " "
//             << v->noParent() << " "
//               << std::endl;
//    }
   return *(tPC.begin());
}
DEFINE_ANOTHER_FWK_MODULE(KineExample);

---