VertexClassifier.cc

Go to the documentation of this file.

/*
 *  VertexClassifier.C
 */

#include <cmath>
#include <cstdlib>
#include <iostream>

#include "HepPDT/ParticleID.hh"

#include "SimTracker/TrackHistory/interface/VertexClassifier.h"

#define update(a, b)  \
  do {                \
    (a) = (a) || (b); \
  } while (0)

VertexClassifier::VertexClassifier(edm::ParameterSet const &config, edm::ConsumesCollector collector)
    : VertexCategories(),
      tracer_(config, collector),
      hepMCLabel_(config.getUntrackedParameter<edm::InputTag>("hepMC")),
      particleDataTableToken_(collector.esConsumes()) {
  collector.consumes<edm::HepMCProduct>(hepMCLabel_);
  // Set the history depth after hadronization
  tracer_.depth(-2);

  // Set the minimum decay length for detecting long decays
  longLivedDecayLength_ = config.getUntrackedParameter<double>("longLivedDecayLength");

  // Set the distance for clustering vertices
  vertexClusteringDistance_ = config.getUntrackedParameter<double>("vertexClusteringDistance");
}

void VertexClassifier::newEvent(edm::Event const &event, edm::EventSetup const &setup) {
  // Get the new event information for the tracer
  tracer_.newEvent(event, setup);

  // Get hepmc of the event
  event.getByLabel(hepMCLabel_, mcInformation_);

  // Get the partivle data table
  particleDataTable_ = setup.getHandle(particleDataTableToken_);

  // Create the list of primary vertices associated to the event
  genPrimaryVertices();
}

VertexClassifier const &VertexClassifier::evaluate(reco::VertexBaseRef const &vertex) {
  // Initializing the category vector
  reset();

  // Associate and evaluate the vertex history (check for fakes)
  if (tracer_.evaluate(vertex)) {
    // Get all the information related to the simulation details
    simulationInformation();

    // Get all the information related to decay process
    processesAtGenerator();

    // Get information about conversion and other interactions
    processesAtSimulation();

    // Get geometrical information about the vertices
    vertexInformation();

    // Check for unkown classification
    unknownVertex();
  } else
    flags_[Fake] = true;

  return *this;
}

VertexClassifier const &VertexClassifier::evaluate(TrackingVertexRef const &vertex) {
  // Initializing the category vector
  reset();

  // Trace the history for the given TP
  tracer_.evaluate(vertex);

  // Check for a reconstructed track
  if (tracer_.recoVertex().isNonnull())
    flags_[Reconstructed] = true;
  else
    flags_[Reconstructed] = false;

  // Get all the information related to the simulation details
  simulationInformation();

  // Get all the information related to decay process
  processesAtGenerator();

  // Get information about conversion and other interactions
  processesAtSimulation();

  // Get geometrical information about the vertices
  vertexInformation();

  // Check for unkown classification
  unknownVertex();

  return *this;
}

void VertexClassifier::simulationInformation() {
  // Get the event id for the initial TP.
  EncodedEventId eventId = tracer_.simVertex()->eventId();
  // Check for signal events
  flags_[SignalEvent] = !eventId.bunchCrossing() && !eventId.event();
}

void VertexClassifier::processesAtGenerator() {
  // Get the generated vetices from track history
  VertexHistory::GenVertexTrail const &genVertexTrail = tracer_.genVertexTrail();

  // Loop over the generated vertices
  for (VertexHistory::GenVertexTrail::const_iterator ivertex = genVertexTrail.begin(); ivertex != genVertexTrail.end();
       ++ivertex) {
    // Get the pointer to the vertex by removing the const-ness (no const methos
    // in HepMC::GenVertex)
    HepMC::GenVertex *vertex = const_cast<HepMC::GenVertex *>(*ivertex);

    // Loop over the sources looking for specific decays
    for (HepMC::GenVertex::particle_iterator iparent = vertex->particles_begin(HepMC::parents);
         iparent != vertex->particles_end(HepMC::parents);
         ++iparent) {
      // Collect the pdgid of the parent
      int pdgid = std::abs((*iparent)->pdg_id());
      // Get particle type
      HepPDT::ParticleID particleID(pdgid);

      // Check if the particle type is valid one
      if (particleID.isValid()) {
        // Get particle data
        ParticleData const *particleData = particleDataTable_->particle(particleID);
        // Check if the particle exist in the table
        if (particleData) {
          // Check if their life time is bigger than longLivedDecayLength_
          if (particleData->lifetime() > longLivedDecayLength_) {
            // Check for B, C weak decays and long lived decays
            update(flags_[BWeakDecay], particleID.hasBottom());
            update(flags_[CWeakDecay], particleID.hasCharm());
            update(flags_[LongLivedDecay], true);
          }
          // Check Tau, Ks and Lambda decay
          update(flags_[TauDecay], pdgid == 15);
          update(flags_[KsDecay], pdgid == 310);
          update(flags_[LambdaDecay], pdgid == 3122);
          update(flags_[JpsiDecay], pdgid == 443);
          update(flags_[XiDecay], pdgid == 3312);
          update(flags_[OmegaDecay], pdgid == 3334);
          update(flags_[SigmaPlusDecay], pdgid == 3222);
          update(flags_[SigmaMinusDecay], pdgid == 3112);
        }
      }
    }
  }
}

void VertexClassifier::processesAtSimulation() {
  VertexHistory::SimVertexTrail const &simVertexTrail = tracer_.simVertexTrail();

  for (VertexHistory::SimVertexTrail::const_iterator ivertex = simVertexTrail.begin(); ivertex != simVertexTrail.end();
       ++ivertex) {
    // pdgid of the real source parent vertex
    int pdgid = 0;

    // select the original source in case of combined vertices
    bool flag = false;
    TrackingVertex::tp_iterator itd, its;

    for (its = (*ivertex)->sourceTracks_begin(); its != (*ivertex)->sourceTracks_end(); ++its) {
      for (itd = (*ivertex)->daughterTracks_begin(); itd != (*ivertex)->daughterTracks_end(); ++itd)
        if (itd != its) {
          flag = true;
          break;
        }
      if (flag)
        break;
    }
    // Collect the pdgid of the original source track
    if (its != (*ivertex)->sourceTracks_end())
      pdgid = std::abs((*its)->pdgId());
    else
      pdgid = 0;

    // Geant4 process type is selected using first Geant4 vertex assigned to
    // the TrackingVertex
    unsigned int processG4 = 0;

    if ((*ivertex)->nG4Vertices() > 0) {
      processG4 = (*(*ivertex)->g4Vertices_begin()).processType();
    }

    unsigned int process = g4toCMSProcMap_.processId(processG4);

    // Flagging all the different processes
    update(flags_[KnownProcess], process != CMS::Undefined && process != CMS::Unknown && process != CMS::Primary);

    update(flags_[UndefinedProcess], process == CMS::Undefined);
    update(flags_[UnknownProcess], process == CMS::Unknown);
    update(flags_[PrimaryProcess], process == CMS::Primary);
    update(flags_[HadronicProcess], process == CMS::Hadronic);
    update(flags_[DecayProcess], process == CMS::Decay);
    update(flags_[ComptonProcess], process == CMS::Compton);
    update(flags_[AnnihilationProcess], process == CMS::Annihilation);
    update(flags_[EIoniProcess], process == CMS::EIoni);
    update(flags_[HIoniProcess], process == CMS::HIoni);
    update(flags_[MuIoniProcess], process == CMS::MuIoni);
    update(flags_[PhotonProcess], process == CMS::Photon);
    update(flags_[MuPairProdProcess], process == CMS::MuPairProd);
    update(flags_[ConversionsProcess], process == CMS::Conversions);
    update(flags_[EBremProcess], process == CMS::EBrem);
    update(flags_[SynchrotronRadiationProcess], process == CMS::SynchrotronRadiation);
    update(flags_[MuBremProcess], process == CMS::MuBrem);
    update(flags_[MuNuclProcess], process == CMS::MuNucl);

    // Loop over the simulated particles
    for (TrackingVertex::tp_iterator iparticle = (*ivertex)->daughterTracks_begin();
         iparticle != (*ivertex)->daughterTracks_end();
         ++iparticle) {
      if ((*iparticle)->numberOfTrackerLayers()) {
        // Special treatment for decays
        if (process == CMS::Decay) {
          // Get particle type
          HepPDT::ParticleID particleID(pdgid);
          // Check if the particle type is valid one
          if (particleID.isValid()) {
            // Get particle data
            ParticleData const *particleData = particleDataTable_->particle(particleID);
            // Check if the particle exist in the table
            if (particleData) {
              // Check if their life time is bigger than 1e-14
              if (particleDataTable_->particle(particleID)->lifetime() > longLivedDecayLength_) {
                // Check for B, C weak decays and long lived decays
                update(flags_[BWeakDecay], particleID.hasBottom());
                update(flags_[CWeakDecay], particleID.hasCharm());
                update(flags_[LongLivedDecay], true);
              }
              // Check Tau, Ks and Lambda decay
              update(flags_[TauDecay], pdgid == 15);
              update(flags_[KsDecay], pdgid == 310);
              update(flags_[LambdaDecay], pdgid == 3122);
              update(flags_[JpsiDecay], pdgid == 443);
              update(flags_[XiDecay], pdgid == 3312);
              update(flags_[OmegaDecay], pdgid == 3334);
              update(flags_[SigmaPlusDecay], pdgid == 3222);
              update(flags_[SigmaMinusDecay], pdgid == 3112);
            }
          }
        }
      }
    }
  }
}

void VertexClassifier::vertexInformation() {
  // Helper class for clusterization
  typedef std::multimap<double, HepMC::ThreeVector> Clusters;
  typedef std::pair<double, HepMC::ThreeVector> ClusterPair;

  Clusters clusters;

  // Get the main primary vertex from the list
  GeneratedPrimaryVertex const &genpv = genpvs_.back();

  // Get the generated history of the tracks
  const VertexHistory::GenVertexTrail &genVertexTrail = tracer_.genVertexTrail();

  // Unit transformation from mm to cm
  double const mm = 0.1;

  // Loop over the generated vertexes
  for (VertexHistory::GenVertexTrail::const_iterator ivertex = genVertexTrail.begin(); ivertex != genVertexTrail.end();
       ++ivertex) {
    // Check vertex exist
    if (*ivertex) {
      // Measure the distance2 respecto the primary vertex
      HepMC::ThreeVector p = (*ivertex)->point3d();
      double distance =
          sqrt(pow(p.x() * mm - genpv.x, 2) + pow(p.y() * mm - genpv.y, 2) + pow(p.z() * mm - genpv.z, 2));

      // If there is not any clusters add the first vertex.
      if (clusters.empty()) {
        clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x() * mm, p.y() * mm, p.z() * mm)));
        continue;
      }

      // Check if there is already a cluster in the given distance from primary
      // vertex
      Clusters::const_iterator icluster = clusters.lower_bound(distance - vertexClusteringDistance_);

      if (icluster == clusters.upper_bound(distance + vertexClusteringDistance_)) {
        clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x() * mm, p.y() * mm, p.z() * mm)));
        continue;
      }

      bool cluster = false;

      // Looping over the vertex clusters of a given distance from primary
      // vertex
      for (; icluster != clusters.upper_bound(distance + vertexClusteringDistance_); ++icluster) {
        double difference = sqrt(pow(p.x() * mm - icluster->second.x(), 2) + pow(p.y() * mm - icluster->second.y(), 2) +
                                 pow(p.z() * mm - icluster->second.z(), 2));

        if (difference < vertexClusteringDistance_) {
          cluster = true;
          break;
        }
      }

      if (!cluster)
        clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x() * mm, p.y() * mm, p.z() * mm)));
    }
  }

  const VertexHistory::SimVertexTrail &simVertexTrail = tracer_.simVertexTrail();

  // Loop over the generated particles
  for (VertexHistory::SimVertexTrail::const_reverse_iterator ivertex = simVertexTrail.rbegin();
       ivertex != simVertexTrail.rend();
       ++ivertex) {
    // Look for those with production vertex
    TrackingVertex::LorentzVector p = (*ivertex)->position();

    double distance = sqrt(pow(p.x() - genpv.x, 2) + pow(p.y() - genpv.y, 2) + pow(p.z() - genpv.z, 2));

    // If there is not any clusters add the first vertex.
    if (clusters.empty()) {
      clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x(), p.y(), p.z())));
      continue;
    }

    // Check if there is already a cluster in the given distance from primary
    // vertex
    Clusters::const_iterator icluster = clusters.lower_bound(distance - vertexClusteringDistance_);

    if (icluster == clusters.upper_bound(distance + vertexClusteringDistance_)) {
      clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x(), p.y(), p.z())));
      continue;
    }

    bool cluster = false;

    // Looping over the vertex clusters of a given distance from primary vertex
    for (; icluster != clusters.upper_bound(distance + vertexClusteringDistance_); ++icluster) {
      double difference = sqrt(pow(p.x() - icluster->second.x(), 2) + pow(p.y() - icluster->second.y(), 2) +
                               pow(p.z() - icluster->second.z(), 2));

      if (difference < vertexClusteringDistance_) {
        cluster = true;
        break;
      }
    }

    if (!cluster)
      clusters.insert(ClusterPair(distance, HepMC::ThreeVector(p.x(), p.y(), p.z())));
  }

  if (clusters.size() == 1)
    flags_[PrimaryVertex] = true;
  else if (clusters.size() == 2)
    flags_[SecondaryVertex] = true;
  else
    flags_[TertiaryVertex] = true;
}

bool VertexClassifier::isFinalstateParticle(const HepMC::GenParticle *p) {
  return !p->end_vertex() && p->status() == 1;
}

bool VertexClassifier::isCharged(const HepMC::GenParticle *p) {
  const ParticleData *part = particleDataTable_->particle(p->pdg_id());
  if (part)
    return part->charge() != 0;
  else {
    // the new/improved particle table doesn't know anti-particles
    return particleDataTable_->particle(-p->pdg_id()) != nullptr;
  }
}

void VertexClassifier::genPrimaryVertices() {
  genpvs_.clear();

  const HepMC::GenEvent *event = mcInformation_->GetEvent();

  if (event) {
    // Loop over the different GenVertex
    for (HepMC::GenEvent::vertex_const_iterator ivertex = event->vertices_begin(); ivertex != event->vertices_end();
         ++ivertex) {
      bool hasParentVertex = false;

      // Loop over the parents looking to see if they are coming from a
      // production vertex
      for (HepMC::GenVertex::particle_iterator iparent = (*ivertex)->particles_begin(HepMC::parents);
           iparent != (*ivertex)->particles_end(HepMC::parents);
           ++iparent)
        if ((*iparent)->production_vertex()) {
          hasParentVertex = true;
          break;
        }

      // Reject those vertices with parent vertices
      if (hasParentVertex)
        continue;

      // Get the position of the vertex
      HepMC::FourVector pos = (*ivertex)->position();

      double const mm = 0.1;

      GeneratedPrimaryVertex pv(pos.x() * mm, pos.y() * mm, pos.z() * mm);

      std::vector<GeneratedPrimaryVertex>::iterator ientry = genpvs_.begin();

      // Search for a VERY close vertex in the list
      for (; ientry != genpvs_.end(); ++ientry) {
        double distance = sqrt(pow(pv.x - ientry->x, 2) + pow(pv.y - ientry->y, 2) + pow(pv.z - ientry->z, 2));
        if (distance < vertexClusteringDistance_)
          break;
      }

      // Check if there is not a VERY close vertex and added to the list
      if (ientry == genpvs_.end())
        ientry = genpvs_.insert(ientry, pv);

      // Add the vertex barcodes to the new or existent vertices
      ientry->genVertex.push_back((*ivertex)->barcode());

      // Collect final state descendants
      for (HepMC::GenVertex::particle_iterator idecendants = (*ivertex)->particles_begin(HepMC::descendants);
           idecendants != (*ivertex)->particles_end(HepMC::descendants);
           ++idecendants) {
        if (isFinalstateParticle(*idecendants))
          if (find(ientry->finalstateParticles.begin(), ientry->finalstateParticles.end(), (*idecendants)->barcode()) ==
              ientry->finalstateParticles.end()) {
            ientry->finalstateParticles.push_back((*idecendants)->barcode());
            HepMC::FourVector m = (*idecendants)->momentum();

            ientry->ptot.setPx(ientry->ptot.px() + m.px());
            ientry->ptot.setPy(ientry->ptot.py() + m.py());
            ientry->ptot.setPz(ientry->ptot.pz() + m.pz());
            ientry->ptot.setE(ientry->ptot.e() + m.e());
            ientry->ptsq += m.perp() * m.perp();

            if (m.perp() > 0.8 && std::abs(m.pseudoRapidity()) < 2.5 && isCharged(*idecendants))
              ientry->nGenTrk++;
          }
      }
    }
  }

  std::sort(genpvs_.begin(), genpvs_.end());
}