KineExample.cc

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#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/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 "MagneticField/Engine/interface/MagneticField.h"
//#include "MagneticField/Records/interface/IdealMagneticField.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)
{
  token_tracks = consumes<TrackCollection>(iConfig.getParameter<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";
//   token_TrackTruth = consumes<TrackingParticleCollection>(edm::InputTag("trackingtruth", "TrackTruth"));
  token_VertexTruth = consumes<TrackingVertexCollection>(edm::InputTag("trackingtruth", "VertexTruth"));
}


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

void KineExample::beginRun(Run const& run, EventSetup const& setup){

//   edm::ESHandle<MagneticField> magField;
//   setup.get<IdealMagneticFieldRecord>().get(magField);
//   tree.reset(new SimpleVertexTree("VertexFitter", magField.product()));
}


void KineExample::endJob() {
}

//
// member functions
//

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

  cout << "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.getByToken(token_tracks, tks);
  if (!tks.isValid()) {
    cout
      << "Couln't find track collection: " << 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);

     cout  << "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);
      if (!tv.isValid()) cout << "KVF failed\n";
      else std::cout << "KVF fit 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 = 0.0000001;
      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;
      cout <<"Simple vertex fit with KinematicParticleVertexFitter:\n";
      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 << "\nGlobal 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.getByToken(token_TrackTruth, TPCollectionH);
//   const TrackingParticleCollection tPC = *(TPCollectionH.product());
//       reco::RecoToSimCollection recSimColl=associatorForParamAtPca->associateRecoToSim(tks,
//                                        TPCollectionH,
//                                        &iEvent,
//                                                                            &iSetup);
//
//       tree->fill(tv, &sv, &recSimColl);
//     }

    }
  }

  }
  catch (std::exception & err) {
    cout  << "Exception during event number: " << iEvent.id()
      << "\n" << err.what() << "\n";
  }

}

void KineExample::printout(const RefCountedKinematicVertex& myVertex) const
{
  if (myVertex->vertexIsValid()) {
    cout << "Decay vertex: " << myVertex->position() <<myVertex->chiSquared()<< " "<<myVertex->degreesOfFreedom()<<endl;
  } else cout << "Decay vertex Not valid\n";
}

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

//and their joint covariance matrix:
//SK:uncomment if needed  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
{
  if (!myTree->isValid()) {
    cout <<"Tree is invalid. Fit failed.\n";
    return;
  }

//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.getByToken(token_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_FWK_MODULE(KineExample);