ConversionTools.cc

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#include "CommonTools/Egamma/interface/ConversionTools.h"
#include "DataFormats/EgammaCandidates/interface/Conversion.h"
#include "DataFormats/GsfTrackReco/interface/GsfTrack.h"
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/Common/interface/RefToPtr.h"
#include "DataFormats/Math/interface/deltaPhi.h"
#include "DataFormats/Math/interface/deltaR.h"

#include <TMath.h>

using namespace edm;
using namespace reco;

//--------------------------------------------------------------------------------------------------
bool ConversionTools::isGoodConversion(const Conversion &conv,
                                       const math::XYZPoint &beamspot,
                                       float lxyMin,
                                       float probMin,
                                       unsigned int nHitsBeforeVtxMax) {
  //Check if a given conversion candidate passes the conversion selection cuts

  const reco::Vertex &vtx = conv.conversionVertex();

  //vertex validity
  if (!vtx.isValid())
    return false;

  //fit probability
  if (TMath::Prob(vtx.chi2(), vtx.ndof()) < probMin)
    return false;

  //compute transverse decay length
  math::XYZVector mom(conv.refittedPairMomentum());
  double dbsx = vtx.x() - beamspot.x();
  double dbsy = vtx.y() - beamspot.y();
  double lxy = (mom.x() * dbsx + mom.y() * dbsy) / mom.rho();

  //transverse decay length
  if (lxy < lxyMin)
    return false;

  //loop through daughters to check nhitsbeforevtx
  for (std::vector<uint8_t>::const_iterator it = conv.nHitsBeforeVtx().begin(); it != conv.nHitsBeforeVtx().end();
       ++it) {
    if ((*it) > nHitsBeforeVtxMax)
      return false;
  }

  return true;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(const reco::GsfElectron &ele,
                                        const reco::Conversion &conv,
                                        bool allowCkfMatch,
                                        bool allowAmbiguousGsfMatch) {
  //check if a given GsfElectron matches a given conversion (no quality cuts applied)
  //matching is always attempted through the gsf track ref, and optionally attempted through the
  //closest ctf track ref

  const std::vector<edm::RefToBase<reco::Track> > &convTracks = conv.tracks();
  for (std::vector<edm::RefToBase<reco::Track> >::const_iterator it = convTracks.begin(); it != convTracks.end();
       ++it) {
    if (ele.reco::GsfElectron::gsfTrack().isNonnull() && ele.reco::GsfElectron::gsfTrack().id() == it->id() &&
        ele.reco::GsfElectron::gsfTrack().key() == it->key())
      return true;
    else if (allowCkfMatch && ele.reco::GsfElectron::closestCtfTrackRef().isNonnull() &&
             ele.reco::GsfElectron::closestCtfTrackRef().id() == it->id() &&
             ele.reco::GsfElectron::closestCtfTrackRef().key() == it->key())
      return true;
    if (allowAmbiguousGsfMatch) {
      for (auto const &tk : ele.ambiguousGsfTracks()) {
        if (tk.isNonnull() && tk.id() == it->id() && tk.key() == it->key())
          return true;
      }
    }
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(const reco::GsfElectronCore &eleCore,
                                        const reco::Conversion &conv,
                                        bool allowCkfMatch) {
  //check if a given GsfElectronCore matches a given conversion (no quality cuts applied)
  //matching is always attempted through the gsf track ref, and optionally attempted through the
  //closest ctf track ref

  for (const auto &trkRef : conv.tracks()) {
    if (eleCore.gsfTrack().isNonnull() && eleCore.gsfTrack().id() == trkRef.id() &&
        eleCore.gsfTrack().key() == trkRef.key())
      return true;
    else if (allowCkfMatch && eleCore.ctfTrack().isNonnull() && eleCore.ctfTrack().id() == trkRef.id() &&
             eleCore.ctfTrack().key() == trkRef.key())
      return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(
    const reco::SuperCluster &sc, const reco::Conversion &conv, float dRMax, float dEtaMax, float dPhiMax) {
  //check if a given SuperCluster matches a given conversion (no quality cuts applied)
  //matching is geometric between conversion momentum and vector joining conversion vertex
  //to supercluster position

  math::XYZVector mom(conv.refittedPairMomentum());

  const math::XYZPoint &scpos(sc.position());
  math::XYZPoint cvtx(conv.conversionVertex().position());

  math::XYZVector cscvector = scpos - cvtx;
  float dR = reco::deltaR(mom, cscvector);
  float dEta = mom.eta() - cscvector.eta();
  float dPhi = reco::deltaPhi(mom.phi(), cscvector.phi());

  if (dR > dRMax)
    return false;
  if (dEta > dEtaMax)
    return false;
  if (dPhi > dPhiMax)
    return false;

  return true;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(const edm::RefToBase<reco::Track> &trk, const reco::Conversion &conv) {
  //check if given track matches given conversion (matching by ref)

  if (trk.isNull())
    return false;

  const std::vector<edm::RefToBase<reco::Track> > &convTracks = conv.tracks();
  for (std::vector<edm::RefToBase<reco::Track> >::const_iterator it = convTracks.begin(); it != convTracks.end();
       ++it) {
    if (trk.id() == it->id() && trk.key() == it->key())
      return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(const reco::TrackRef &trk, const reco::Conversion &conv) {
  //check if given track matches given conversion (matching by ref)

  if (trk.isNull())
    return false;

  const std::vector<edm::RefToBase<reco::Track> > &convTracks = conv.tracks();
  for (std::vector<edm::RefToBase<reco::Track> >::const_iterator it = convTracks.begin(); it != convTracks.end();
       ++it) {
    if (trk.id() == it->id() && trk.key() == it->key())
      return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::matchesConversion(const reco::GsfTrackRef &trk, const reco::Conversion &conv) {
  //check if given track matches given conversion (matching by ref)

  if (trk.isNull())
    return false;

  const std::vector<edm::RefToBase<reco::Track> > &convTracks = conv.tracks();
  for (std::vector<edm::RefToBase<reco::Track> >::const_iterator it = convTracks.begin(); it != convTracks.end();
       ++it) {
    if (trk.id() == it->id() && trk.key() == it->key())
      return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::hasMatchedConversion(const reco::GsfElectron &ele,
                                           const reco::ConversionCollection &convCol,
                                           const math::XYZPoint &beamspot,
                                           bool allowCkfMatch,
                                           float lxyMin,
                                           float probMin,
                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given electron candidate matches to at least one conversion candidate in the
  //collection which also passes the selection cuts, optionally match with the closestckf track in
  //in addition to just the gsf track (enabled in default arguments)

  for (auto const &it : convCol) {
    if (!matchesConversion(ele, it, allowCkfMatch))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::hasMatchedConversion(const reco::TrackRef &trk,
                                           const reco::ConversionCollection &convCol,
                                           const math::XYZPoint &beamspot,
                                           float lxyMin,
                                           float probMin,
                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given track matches to at least one conversion candidate in the
  //collection which also passes the selection cuts

  if (trk.isNull())
    return false;

  for (auto const &it : convCol) {
    if (!matchesConversion(trk, it))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::hasMatchedConversion(const reco::SuperCluster &sc,
                                           const reco::ConversionCollection &convCol,
                                           const math::XYZPoint &beamspot,
                                           float dRMax,
                                           float dEtaMax,
                                           float dPhiMax,
                                           float lxyMin,
                                           float probMin,
                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given SuperCluster matches to at least one conversion candidate in the
  //collection which also passes the selection cuts

  for (auto const &it : convCol) {
    if (!matchesConversion(sc, it))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    return true;
  }

  return false;
}

//--------------------------------------------------------------------------------------------------
reco::Conversion const *ConversionTools::matchedConversion(const reco::GsfElectron &ele,
                                                           const reco::ConversionCollection &convCol,
                                                           const math::XYZPoint &beamspot,
                                                           bool allowCkfMatch,
                                                           float lxyMin,
                                                           float probMin,
                                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given electron candidate matches to at least one conversion candidate in the
  //collection which also passes the selection cuts, optionally match with the closestckf track in
  //in addition to just the gsf track (enabled in default arguments)
  //If multiple conversions are found, returned reference corresponds to minimum
  //conversion radius

  reco::Conversion const *match = nullptr;

  double minRho = 999.;
  for (auto const &it : convCol) {
    float rho = it.conversionVertex().position().rho();
    if (rho > minRho)
      continue;
    if (!matchesConversion(ele, it, allowCkfMatch))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    minRho = rho;
    match = &it;
  }

  return match;
}

//--------------------------------------------------------------------------------------------------
reco::Conversion const *ConversionTools::matchedConversion(const reco::GsfElectronCore &eleCore,
                                                           const reco::ConversionCollection &convCol,
                                                           const math::XYZPoint &beamspot,
                                                           bool allowCkfMatch,
                                                           float lxyMin,
                                                           float probMin,
                                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given electron candidate matches to at least one conversion candidate in the
  //collection which also passes the selection cuts, optionally match with the closestckf track in
  //in addition to just the gsf track (enabled in default arguments)
  //If multiple conversions are found, returned reference corresponds to minimum
  //conversion radius

  reco::Conversion const *match = nullptr;

  double minRho = 999.;
  for (auto const &it : convCol) {
    float rho = it.conversionVertex().position().rho();
    if (rho > minRho)
      continue;
    if (!matchesConversion(eleCore, it, allowCkfMatch))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    minRho = rho;
    match = &it;
  }

  return match;
}

//--------------------------------------------------------------------------------------------------
reco::Conversion const *ConversionTools::matchedConversion(const reco::TrackRef &trk,
                                                           const reco::ConversionCollection &convCol,
                                                           const math::XYZPoint &beamspot,
                                                           float lxyMin,
                                                           float probMin,
                                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given track matches to at least one conversion candidate in the
  //collection which also passes the selection cuts
  //If multiple conversions are found, returned reference corresponds to minimum
  //conversion radius

  reco::Conversion const *match = nullptr;

  if (trk.isNull())
    return match;

  double minRho = 999.;
  for (auto const &it : convCol) {
    float rho = it.conversionVertex().position().rho();
    if (rho > minRho)
      continue;
    if (!matchesConversion(trk, it))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    minRho = rho;
    match = &it;
  }

  return match;
}

//--------------------------------------------------------------------------------------------------
reco::Conversion const *ConversionTools::matchedConversion(const reco::SuperCluster &sc,
                                                           const reco::ConversionCollection &convCol,
                                                           const math::XYZPoint &beamspot,
                                                           float dRMax,
                                                           float dEtaMax,
                                                           float dPhiMax,
                                                           float lxyMin,
                                                           float probMin,
                                                           unsigned int nHitsBeforeVtxMax) {
  //check if a given SuperCluster matches to at least one conversion candidate in the
  //collection which also passes the selection cuts
  //If multiple conversions are found, returned reference corresponds to minimum
  //conversion radius

  reco::Conversion const *match = nullptr;

  double minRho = 999.;
  for (auto const &it : convCol) {
    float rho = it.conversionVertex().position().rho();
    if (rho > minRho)
      continue;
    if (!matchesConversion(sc, it, dRMax, dEtaMax, dPhiMax))
      continue;
    if (!isGoodConversion(it, beamspot, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    minRho = rho;
    match = &it;
  }

  return match;
}

//--------------------------------------------------------------------------------------------------
bool ConversionTools::hasMatchedPromptElectron(const reco::SuperClusterRef &sc,
                                               const reco::GsfElectronCollection &eleCol,
                                               const reco::ConversionCollection &convCol,
                                               const math::XYZPoint &beamspot,
                                               bool allowCkfMatch,
                                               float lxyMin,
                                               float probMin,
                                               unsigned int nHitsBeforeVtxMax) {
  return !(matchedPromptElectron(sc, eleCol, convCol, beamspot, allowCkfMatch, lxyMin, probMin, nHitsBeforeVtxMax) ==
           nullptr);
}

//--------------------------------------------------------------------------------------------------
reco::GsfElectron const *ConversionTools::matchedPromptElectron(const reco::SuperClusterRef &sc,
                                                                const reco::GsfElectronCollection &eleCol,
                                                                const reco::ConversionCollection &convCol,
                                                                const math::XYZPoint &beamspot,
                                                                bool allowCkfMatch,
                                                                float lxyMin,
                                                                float probMin,
                                                                unsigned int nHitsBeforeVtxMax) {
  //check if a given SuperCluster matches to at least one GsfElectron having zero expected inner hits
  //and not matching any conversion in the collection passing the quality cuts

  reco::GsfElectron const *match = nullptr;

  if (sc.isNull())
    return match;

  for (auto const &it : eleCol) {
    //match electron to supercluster
    if (it.superCluster() != sc)
      continue;

    //check expected inner hits
    if (it.gsfTrack()->hitPattern().numberOfLostHits(reco::HitPattern::MISSING_INNER_HITS) > 0)
      continue;

    //check if electron is matching to a conversion
    if (hasMatchedConversion(it, convCol, beamspot, allowCkfMatch, lxyMin, probMin, nHitsBeforeVtxMax))
      continue;

    match = &it;
  }

  return match;
}

//--------------------------------------------------------------------------------------------------
float ConversionTools::getVtxFitProb(const reco::Conversion *conv) {
  if (conv != nullptr) {
    const reco::Vertex &vtx = conv->conversionVertex();
    if (vtx.isValid()) {
      return TMath::Prob(vtx.chi2(), vtx.ndof());
    }
  }
  return -1;
}