FilterCalculator.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#include <hlt/softwaretrigger/calculations/FilterCalculator.h>
#include <hlt/softwaretrigger/calculations/utilities.h>
 
#include <Math/Vector3D.h>
#include <Math/Vector4D.h>
#include <Math/VectorUtil.h>
 
#include <mdst/dataobjects/TrackFitResult.h>
#include <mdst/dataobjects/HitPatternCDC.h>
 
#include <analysis/dataobjects/Particle.h>
#include <analysis/VertexFitting/KFit/VertexFitKFit.h>
 
#include <framework/logging/Logger.h>
 
#include <numeric>
#include <stdexcept>
#include <optional>
 
using namespace Belle2;
using namespace SoftwareTrigger;
 
struct MaximumPtTrack {
  double pT = NAN;
  const Track* track = nullptr;
  double clusterEnergySumCMS = 0;
  double clusterEnergySumLab = 0;
  double pCMS = NAN;
  double pLab = NAN;
  ROOT::Math::PxPyPzEVector p4CMS;
  ROOT::Math::PxPyPzEVector p4Lab;
};
 
struct SelectedECLCluster {
  const ECLCluster* cluster = nullptr;
  double energyCMS = NAN;
  double energyLab = NAN;
  ROOT::Math::PxPyPzEVector p4CMS;
  ROOT::Math::PxPyPzEVector p4Lab;
  bool isTrack = false;
  double clusterTime = NAN;
};
 
const double flatBoundaries[10] = {0., 19., 22., 25., 30., 35., 45., 60., 90., 180.};
 
 
FilterCalculator::FilterCalculator() : m_bitsNN("CDCTriggerNNBits")
{
 
}
 
void FilterCalculator::requireStoreArrays()
{
  m_tracks.isRequired();
  m_eclClusters.isRequired();
  m_l1Trigger.isOptional();
  m_bitsNN.isOptional();
}
 
void FilterCalculator::doCalculation(SoftwareTriggerObject& calculationResult)
{
  calculationResult["nTrkLoose"] = 0; 
  calculationResult["nTrkTight"] = 0; 
  calculationResult["ee2leg"] = 0; 
  calculationResult["nEmedium"] = 0; 
  calculationResult["nElow"] = 0; 
  calculationResult["nEhigh"] = 0; 
  calculationResult["nE180Lab"] = 0; 
  calculationResult["nE300Lab"] = 0; 
  calculationResult["nE500Lab"] = 0; 
  calculationResult["nE2000CMS"] = 0; 
  calculationResult["nE4000CMS"] = 0; 
  calculationResult["nE250Lab"] = 0; 
  calculationResult["nMaxEPhotonAcc"] = 0; 
  calculationResult["dphiCmsClust"] = NAN; 
  calculationResult["netChargeLoose"] = 0; 
  calculationResult["maximumPCMS"] = NAN; 
  calculationResult["maximumPLab"] = NAN; 
  calculationResult["eexx"] = 0;
  calculationResult["ee1leg1trk"] = 0; 
  calculationResult["nEhighLowAng"] = 0; 
  calculationResult["nEsingleClust"] = 0; 
  calculationResult["nEsinglePhotonBarrel"] = 0; 
  calculationResult["nEsinglePhotonExtendedBarrel"] = 0; 
  calculationResult["nEsinglePhotonEndcap"] = 0; 
  calculationResult["nEsingleElectronBarrel"] = 0; 
  calculationResult["nEsingleElectronExtendedBarrel"] = 0; 
  calculationResult["nReducedEsinglePhotonReducedBarrel"] = 0; 
  calculationResult["nVetoClust"] = 0; 
  calculationResult["chrgClust2GeV"] = 0; 
  calculationResult["neutClust045GeVAcc"] = 0; 
  calculationResult["neutClust045GeVBarrel"] = 0; 
  calculationResult["singleTagLowMass"] = 0;
  calculationResult["singleTagHighMass"] = 0;
  calculationResult["n2GeVNeutBarrel"] = 0;
  calculationResult["n2GeVNeutEndcap"] = 0;
  calculationResult["n2GeVChrg"] = 0;
  calculationResult["n2GeVPhotonBarrel"] = 0;
  calculationResult["n2GeVPhotonEndcap"] = 0;
  calculationResult["ee1leg"] = 0; 
  calculationResult["ee1leg1clst"] = 0; 
  calculationResult["ee1leg1e"] = 0; 
  calculationResult["ee2clst"] = 0; 
  calculationResult["gg2clst"] = 0; 
  calculationResult["eeee"] = 0;
  calculationResult["eemm"] = 0;
  calculationResult["eexxSelect"] = 0;
  calculationResult["radBhabha"] = 0;
  calculationResult["eeBrem"] = 0;
  calculationResult["isrRadBhabha"] = 0;
  calculationResult["muonPairECL"] = 0;
  calculationResult["ggHighPt"] = 0;
  calculationResult["selectee1leg1trk"] = 0;
  calculationResult["selectee1leg1clst"] = 0;
  calculationResult["selectee"] = 0;
  calculationResult["ggBarrelVL"] = 0;
  calculationResult["ggBarrelLoose"] = 0;
  calculationResult["ggBarrelTight"] = 0;
  calculationResult["ggEndcapVL"] = 0;
  calculationResult["ggEndcapLoose"] = 0;
  calculationResult["ggEndcapTight"] = 0;
  calculationResult["muonPairV"] = 0;
  calculationResult["selectmumu"] = 0;
  calculationResult["singleMuon"] = 0;
  calculationResult["cosmic"] = 0;
  calculationResult["displacedVertex"] = 0;
  calculationResult["eeFlat0"] = 0;
  calculationResult["eeFlat1"] = 0;
  calculationResult["eeFlat2"] = 0;
  calculationResult["eeFlat3"] = 0;
  calculationResult["eeFlat4"] = 0;
  calculationResult["eeFlat5"] = 0;
  calculationResult["eeFlat6"] = 0;
  calculationResult["eeFlat7"] = 0;
  calculationResult["eeFlat8"] = 0;
  calculationResult["eeOneClust"] = 0;
 
  //..New track definitions
  calculationResult["nTrkLooseB"] = 0; 
  calculationResult["nTrkTightB"] = 0; 
  calculationResult["maximumPCMSB"] = NAN; 
  calculationResult["netChargeLooseB"] = 0; 
  calculationResult["muonPairVB"] = 0; 
  calculationResult["eeBremB"] = 0; 
  calculationResult["singleTagLowMassB"] = 0; 
  calculationResult["singleTagHighMassB"] = 0; 
  calculationResult["radBhabhaB"] = 0; 
  //..Tracks without a requirement on nCDCHits
  calculationResult["nTrackC"] = 0; 
  calculationResult["maximumPCMSC"] = NAN; 
  calculationResult["pCmsNegC"] = NAN; 
  calculationResult["clusterENegC"] = NAN; 
  calculationResult["pCmsPosC"] = NAN; 
  calculationResult["clusterEPosC"] = NAN; 
  calculationResult["dPhiCmsC"] = NAN; 
  // Passed on L1 information
  if (m_l1Trigger.isValid()) {
    calculationResult["l1_trigger_random"] = m_l1Trigger->getTimType() == TRGSummary::ETimingType::TTYP_RAND;
    calculationResult["l1_trigger_delayed_bhabha"] = m_l1Trigger->getTimType() == TRGSummary::ETimingType::TTYP_DPHY;
    calculationResult["l1_trigger_poisson"] = m_l1Trigger->getTimType() == TRGSummary::ETimingType::TTYP_POIS;
    bool bha3d;
    try {
      bha3d = m_l1Trigger->testPsnm("bha3d");
    } catch (const std::exception&) {
      bha3d = false;
    }
    bool bhapurPsnm;
    try {
      bhapurPsnm = m_l1Trigger->testPsnm("bhapur");
    } catch (const std::exception&) {
      bhapurPsnm = false;
    }
    bool bhapurFtdl;
    try {
      bhapurFtdl = m_l1Trigger->testFtdl("bhapur");
    } catch (const std::exception&) {
      bhapurFtdl = false;
    }
    bool lml1;
    try {
      lml1 = m_l1Trigger->testPsnm("lml1");
    } catch (const std::exception&) {
      lml1 = false;
    }
    bool l1_bit_f;
    try {
      l1_bit_f = m_l1Trigger->testPsnm("fpre");
    } catch (const std::exception&) {
      l1_bit_f = false;
    }
    calculationResult["bha3d"] = bha3d;
    calculationResult["bhapur"] = bhapurPsnm;
    calculationResult["bhapur_lml1"] = lml1 and bhapurFtdl;
    calculationResult["l1_bit_f"] = l1_bit_f;
  } else {
    calculationResult["l1_trigger_random"] = 1; // save every event if no L1 trigger info
    calculationResult["l1_trigger_delayed_bhabha"] = 0;
    calculationResult["l1_trigger_poisson"] = 0;
    calculationResult["bha3d"] = 0;
    calculationResult["bhapur"] = 0;
    calculationResult["bhapur_lml1"] = 0;
    calculationResult["l1_bit_f"] = 0;
  }
 
  // Every 256th event has CDC NN trigger information
  calculationResult["l1_trg_NN_info"] = 0;
  if (m_bitsNN.isValid() and m_bitsNN.getEntries() > 0) {calculationResult["l1_trg_NN_info"] = 1;}
 
  calculationResult["true"] = 1;
  calculationResult["false"] = 0;
 
  // Some utilities
  // TODO: into constructor
  ClusterUtils cUtil;
  const ROOT::Math::XYZVector clustervertex = cUtil.GetIPPosition();
  PCmsLabTransform boostrotate;
  ROOT::Math::PxPyPzEVector p4ofCOM;
  p4ofCOM.SetPxPyPzE(0, 0, 0, boostrotate.getCMSEnergy());
 
  // Pointers to the two tracks with the maximum pt
  std::map<short, std::optional<MaximumPtTrack>> maximumPtTracks = {
    { -1, {}}, {1,  {}}
  };
 
  // Pointer to the two tracks with maximum pt without a cut applied on z0 (used for cosmic trigger)
  std::map<short, std::optional<MaximumPtTrack>> maximumPtTracksWithoutZCut = {
    { -1, {}}, {1, {}}
  };
 
  //..Pointers to the two "C" tracks with maximum pCms (no requirement on nCDC hits)
  std::map<short, std::optional<MaximumPtTrack>> maximumPCmsTracksC = {
    { -1, {}}, {1, {}}
  };
 
  //------------------------------------------------------------
  // --- Track variables -- //
  for (const Track& track : m_tracks) {
    const TrackFitResult* trackFitResult = track.getTrackFitResultWithClosestMass(Const::pion);
    if (not trackFitResult) {
      // Huh? No track fit result for pion? Ok, lets skip this track
      continue;
    }
 
    //..Track properties. Only use tracks with defined charge.
    const short charge = trackFitResult->getChargeSign();
    if (charge == 0) {continue;}
    const double z0 = trackFitResult->getZ0();
    const ROOT::Math::PxPyPzEVector& momentumLab = trackFitResult->get4Momentum();
    const ROOT::Math::PxPyPzEVector momentumCMS = boostrotate.rotateLabToCms() * momentumLab;
    const double pCMS = momentumCMS.P();
    const double pLab = momentumLab.P();
    const double trackTime = track.getTrackTime();
    const double pT = trackFitResult->getTransverseMomentum();
    const int nCDCHits = (int)(0.5 + trackFitResult->getHitPatternCDC().getNHits());
    double clusterELab = 0.;
    for (auto& cluster : track.getRelationsTo<ECLCluster>()) {
      if (cluster.hasHypothesis(Belle2::ECLCluster::EHypothesisBit::c_nPhotons)) {
        clusterELab += cluster.getEnergy(Belle2::ECLCluster::EHypothesisBit::c_nPhotons);
      }
    }
    const double clusterECMS = clusterELab * pCMS / pLab;
 
 
    //------------------------------------------------------------
    //..New list without a requirement on number of CDC hits
    bool goodTrackCTime = true;
    if (std::abs(trackTime) > 15.) {goodTrackCTime = false;}
    if (std::abs(z0) < 1. and goodTrackCTime and pCMS > 0.2) {
      calculationResult["nTrackC"] += 1;
      if (std::isnan(calculationResult["maximumPCMSC"]) or pCMS > calculationResult["maximumPCMSC"]) {
        calculationResult["maximumPCMSC"] = pCMS;
      }
    }
 
    //..Store maximum pCms positive and negative tracks
    const auto& currentMaximumC = maximumPCmsTracksC.at(charge);
    if (not currentMaximumC or pCMS > currentMaximumC->pCMS) {
      MaximumPtTrack newMaximum;
      newMaximum.pT = pT;
      newMaximum.track = &track;
      newMaximum.pCMS = pCMS;
      newMaximum.pLab = pLab;
      newMaximum.p4CMS = momentumCMS;
      newMaximum.p4Lab = momentumLab;
      newMaximum.clusterEnergySumLab = clusterELab;
      newMaximum.clusterEnergySumCMS = clusterECMS;
      maximumPCmsTracksC[charge] = newMaximum;
    }
 
    //------------------------------------------------------------
    //..Now original loose and tight tracks, which require nCDC hits
    // TODO: Temporary cut on number of CDC hits
    if (nCDCHits == 0) {
      continue;
    }
 
    // Count tight tracks
    if (std::abs(z0) < m_tightTrkZ0) {
      calculationResult["nTrkTight"] += 1;
    }
 
 
    //------------------------------------------------------------
    // Find the maximum pt negative [0] and positive [1] tracks without z0 cut
    const auto& currentMaximum = maximumPtTracksWithoutZCut.at(charge);
    if (not currentMaximum or pT > currentMaximum->pT) {
      MaximumPtTrack newMaximum;
      newMaximum.pT = pT;
      newMaximum.track = &track;
      newMaximum.pCMS = pCMS;
      newMaximum.pLab = pLab;
      newMaximum.p4CMS = momentumCMS;
      newMaximum.p4Lab = momentumLab;
      newMaximum.clusterEnergySumLab = clusterELab;
      newMaximum.clusterEnergySumCMS = clusterECMS;
      maximumPtTracksWithoutZCut[charge] = newMaximum;
    }
 
 
    //------------------------------------------------------------
    // Loose tracks
    if (std::abs(z0) < m_looseTrkZ0) {
      calculationResult["nTrkLoose"] += 1;
      calculationResult["netChargeLoose"] += charge;
 
      if (std::isnan(calculationResult["maximumPCMS"]) or pCMS > calculationResult["maximumPCMS"]) {
        calculationResult["maximumPCMS"] = pCMS;
      }
 
      if (std::isnan(calculationResult["maximumPLab"]) or pLab > calculationResult["maximumPLab"]) {
        calculationResult["maximumPLab"] = pLab;
      }
 
      // Find the maximum pt negative [0] and positive [1] tracks
      const double pTLoose = trackFitResult->getTransverseMomentum();
      const auto& currentMaximumLoose = maximumPtTracks.at(charge);
      if (not currentMaximumLoose or pTLoose > currentMaximumLoose->pT) {
        MaximumPtTrack newMaximum;
        newMaximum.pT = pTLoose;
        newMaximum.track = &track;
        newMaximum.pCMS = pCMS;
        newMaximum.pLab = momentumLab.P();
        newMaximum.p4CMS = momentumCMS;
        newMaximum.p4Lab = momentumLab;
        newMaximum.clusterEnergySumLab = clusterELab;
        newMaximum.clusterEnergySumCMS = clusterECMS;
        maximumPtTracks[charge] = newMaximum;
      }
    }
 
    //..New tighter track definitions.
    //  We can use pCMS and charge from above, because every looseB track is also a loose track
    if (nCDCHits >= 5) {
      if (std::abs(z0) < 1.) {calculationResult["nTrkTightB"] += 1;}
      if (std::abs(z0) < 5.) {
        calculationResult["nTrkLooseB"] += 1;
        calculationResult["netChargeLooseB"] += charge;
        if (std::isnan(calculationResult["maximumPCMSB"]) or pCMS > calculationResult["maximumPCMSB"]) {
          calculationResult["maximumPCMSB"] = pCMS;
 
        }
      }
    }
 
  } // End loop over tracks
 
 
  //------------------------------------------------------------
  //..Store the "C" track calculations
  for (short charge : { -1, 1}) {
    auto& maximumPcmsTrackC = maximumPCmsTracksC.at(charge);
    if (not maximumPcmsTrackC) {
      continue;
    }
 
    //..Calculations for each track
    if (charge == -1) {
      calculationResult["pCmsNegC"] = maximumPcmsTrackC->pCMS;
      calculationResult["clusterENegC"] = maximumPcmsTrackC->clusterEnergySumLab;
    } else {
      calculationResult["pCmsPosC"] = maximumPcmsTrackC->pCMS;
      calculationResult["clusterEPosC"] = maximumPcmsTrackC->clusterEnergySumLab;
    }
  }
 
  //..Calculations using both highest-pCms C tracks
  if (maximumPCmsTracksC.at(-1) and maximumPCmsTracksC.at(1)) {
    const MaximumPtTrack& negativeTrack = *maximumPCmsTracksC.at(-1);
    const MaximumPtTrack& positiveTrack = *maximumPCmsTracksC.at(1);
 
    calculationResult["dPhiCmsC"] = std::abs(ROOT::Math::VectorUtil::DeltaPhi(negativeTrack.p4CMS,
                                             positiveTrack.p4CMS)) * TMath::RadToDeg();
  }
 
 
  //------------------------------------------------------------
  // -- Cluster variables -- //
  std::vector<SelectedECLCluster> selectedClusters;
  for (const ECLCluster& cluster : m_eclClusters) {
    // Use the photon hypothesis, and only look at clusters with times < 200 ns
    const double time = cluster.getTime();
    if (not cluster.hasHypothesis(Belle2::ECLCluster::EHypothesisBit::c_nPhotons) or
        std::abs(time) > 200 or
        cluster.getEnergy(Belle2::ECLCluster::EHypothesisBit::c_nPhotons) < 0.1) {
      continue;
    }
 
    const double dt99 = cluster.getDeltaTime99();
 
    // Store cluster information
    SelectedECLCluster selectedCluster;
    selectedCluster.p4Lab = cUtil.Get4MomentumFromCluster(&cluster, clustervertex,
                                                          Belle2::ECLCluster::EHypothesisBit::c_nPhotons);
    selectedCluster.p4CMS = boostrotate.rotateLabToCms() * selectedCluster.p4Lab; // was clustp4COM
    selectedCluster.cluster = &cluster;
    selectedCluster.clusterTime = time / dt99; // was clustT
    selectedCluster.energyLab = selectedCluster.p4Lab.E();
    selectedCluster.energyCMS = selectedCluster.p4CMS.E(); // was first of ECOMPair
    selectedCluster.isTrack = cluster.isTrack(); // was tempCharge
 
    selectedClusters.push_back(selectedCluster);
 
    if (selectedCluster.energyCMS > m_E2min) {
      calculationResult["nElow"] += 1;
    }
    if (selectedCluster.energyCMS > m_E0min) {
      calculationResult["nEmedium"] += 1;
    }
    if (selectedCluster.energyCMS > m_Ehigh) {
      calculationResult["nEhigh"] += 1;
    }
 
    if (selectedCluster.energyCMS > m_E0min and std::abs(selectedCluster.clusterTime) < 10) {
      calculationResult["nVetoClust"] += 1;
    }
 
 
    //..Single cluster trigger objects use charge, Zernike moment, and thetaLab
    const double thetaLab = selectedCluster.p4Lab.Theta() * TMath::RadToDeg();
    const double zmva = cluster.getZernikeMVA();
    const bool photon = zmva > 0.5 and not selectedCluster.isTrack;
    const bool electron = zmva > 0.5 and selectedCluster.isTrack;
 
    //..For 1 track radiative Bhabha control sample
    if (selectedCluster.energyCMS > 2. and selectedCluster.isTrack) {
      calculationResult["chrgClust2GeV"] += 1;
    }
    if (selectedCluster.energyCMS > 0.45 and not selectedCluster.isTrack) {
      const bool isInAcceptance = 17. < thetaLab and thetaLab < 150.;
      if (isInAcceptance) {calculationResult["neutClust045GeVAcc"] += 1;}
      const bool isInBarrel = 30. < thetaLab and thetaLab < 130.;
      if (isInBarrel) {calculationResult["neutClust045GeVBarrel"] += 1;}
    }
 
 
    // improved 3 cluster (4 cluster) trigger
    const bool notInHighBackgroundEndcapRegion = 18.5 < thetaLab and thetaLab < 139.3;
    if (selectedCluster.energyLab > m_EminLab and notInHighBackgroundEndcapRegion) {
      calculationResult["nE180Lab"] += 1;
    }
 
    if (selectedCluster.energyLab > m_EminLab4Cluster and notInHighBackgroundEndcapRegion) {
      calculationResult["nE300Lab"] += 1;
    }
 
    if (selectedCluster.energyLab > m_EminLab3Cluster and notInHighBackgroundEndcapRegion) {
      calculationResult["nE500Lab"] += 1;
    }
 
    if (selectedCluster.energyCMS > m_Ehigh and notInHighBackgroundEndcapRegion) {
      calculationResult["nE2000CMS"] += 1;
    }
 
    //..For two-photon fusion ALP trigger
    if (selectedCluster.energyLab > 0.25) {
      calculationResult["nE250Lab"] += 1;
    }
    if (selectedCluster.energyCMS > 4.) {
      calculationResult["nE4000CMS"] += 1;
    }
 
    //..Single cluster triggers
    if (selectedCluster.energyCMS > m_EsinglePhoton) {
      calculationResult["nEsingleClust"] += 1;
 
      const bool barrelRegion = thetaLab > 45 and thetaLab < 115;
      const bool extendedBarrelRegion = thetaLab > 30 and thetaLab < 130;
      const bool endcapRegion = (thetaLab > 22 and thetaLab < 45) or (thetaLab > 115 and thetaLab < 145);
 
      if (photon and barrelRegion) {
        calculationResult["nEsinglePhotonBarrel"] += 1;
      }
 
      if (photon and extendedBarrelRegion) {
        calculationResult["nEsinglePhotonExtendedBarrel"] += 1;
      }
 
      if (electron and barrelRegion) {
        calculationResult["nEsingleElectronBarrel"] += 1;
      }
 
      if (electron and extendedBarrelRegion) {
        calculationResult["nEsingleElectronExtendedBarrel"] += 1;
      }
 
      if (photon and endcapRegion) {
        calculationResult["nEsinglePhotonEndcap"] += 1;
      }
    }
 
    if (selectedCluster.energyCMS > m_reducedEsinglePhoton) {
      const bool reducedBarrelRegion = thetaLab > 44 and thetaLab < 98;
 
      if (photon and reducedBarrelRegion) {
        calculationResult["nReducedEsinglePhotonReducedBarrel"] += 1;
      }
    }
 
    if (selectedCluster.energyCMS > m_Ehigh) {
      // TODO: different definition!
      const bool barrelRegion = thetaLab > 32 and thetaLab < 130;
      const bool endcapRegion = (thetaLab > 22 and thetaLab < 32) or (thetaLab > 130 and thetaLab < 145);
      const bool lowAngleRegion = thetaLab < 22 or thetaLab > 145;
 
      if (not selectedCluster.isTrack and barrelRegion) {
        calculationResult["n2GeVNeutBarrel"] += 1;
      }
      if (not selectedCluster.isTrack and endcapRegion) {
        calculationResult["n2GeVNeutEndcap"] += 1;
      }
      if (selectedCluster.isTrack and not lowAngleRegion) {
        calculationResult["n2GeVChrg"] += 1;
      }
      if (lowAngleRegion) {
        calculationResult["nEhighLowAng"] += 1;
      }
      if (photon and barrelRegion) {
        calculationResult["n2GeVPhotonBarrel"] += 1;
      }
      if (photon and endcapRegion) {
        calculationResult["n2GeVPhotonEndcap"] += 1;
      }
    }
  } // end of loop over clusters
 
  //..Order clusters by CMS energy
  std::sort(selectedClusters.begin(), selectedClusters.end(), [](const auto & lhs, const auto & rhs) {
    return lhs.energyCMS > rhs.energyCMS;
  });
 
  // -- Bhabha and two-photon lepton preparation -- //
  for (short charge : { -1, 1}) {
    auto& maximumPtTrack = maximumPtTracks.at(charge);
    if (not maximumPtTrack) {
      continue;
    }
 
    // Single leg Bhabha selections
    if (maximumPtTrack->clusterEnergySumCMS > 4.5) {
      calculationResult["ee1leg"] = 1;
    }
 
    // single muon
    if (maximumPtTrack->pCMS > 3 and maximumPtTrack->clusterEnergySumLab > 0. and maximumPtTrack->clusterEnergySumLab < 1.) {
      calculationResult["singleMuon"] = 1;
    }
  }
 
  // Bhabha selections using two tracks
  if (maximumPtTracks.at(-1) and maximumPtTracks.at(1)) {
    const MaximumPtTrack& negativeTrack = *maximumPtTracks.at(-1);
    const MaximumPtTrack& positiveTrack = *maximumPtTracks.at(1);
 
    double dphi = std::abs(negativeTrack.p4CMS.Phi() - positiveTrack.p4CMS.Phi()) * TMath::RadToDeg();
    if (dphi > 180) {
      dphi = 360 - dphi;
    }
 
    const double negativeClusterSum = negativeTrack.clusterEnergySumCMS;
    const double negativeClusterSumLab = negativeTrack.clusterEnergySumLab;
    const double negativeP = negativeTrack.pCMS;
    const double positiveClusterSum = positiveTrack.clusterEnergySumCMS;
    const double positiveClusterSumLab = positiveTrack.clusterEnergySumLab;
    const double positiveP = positiveTrack.pCMS;
 
    // two leg Bhabha
    const double thetaSum = (negativeTrack.p4CMS.Theta() + positiveTrack.p4CMS.Theta()) * TMath::RadToDeg();
    const double dthetaSum = std::abs(thetaSum - 180);
    const auto back2back = dphi > 175 and dthetaSum < 15;
    if (back2back and negativeClusterSum > 3 and positiveClusterSum > 3 and
        (negativeClusterSum > 4.5 or positiveClusterSum > 4.5)) {
      calculationResult["ee2leg"] = 1;
    }
 
    // one leg one track Bhabha
    if (back2back and ((negativeClusterSum > 4.5 and positiveP > 3) or (positiveClusterSum > 4.5 and negativeP > 3))) {
      calculationResult["ee1leg1trk"] = 1;
    }
 
 
    // one leg plus one electron
    if ((negativeClusterSum > 4.5 and positiveClusterSum > 0.8 * positiveP) or
        (positiveClusterSum > 4.5 and negativeClusterSum > 0.8 * negativeP)) {
      calculationResult["ee1leg1e"] = 1;
    }
 
    // eeee, eemm, mu mu, and radiative Bhabha selection
    const ROOT::Math::PxPyPzEVector p4Miss = p4ofCOM - negativeTrack.p4CMS - positiveTrack.p4CMS;
    const double pmissTheta = p4Miss.Theta() * TMath::RadToDeg();
    const double pmissp = p4Miss.P();
    const double relMissAngle0 = B2Vector3D(negativeTrack.p4CMS.Vect()).Angle(B2Vector3D(p4Miss.Vect())) * TMath::RadToDeg();
    const double relMissAngle1 = B2Vector3D(positiveTrack.p4CMS.Vect()).Angle(B2Vector3D(p4Miss.Vect())) * TMath::RadToDeg();
 
    const bool electronEP = positiveClusterSum > 0.8 * positiveP or negativeClusterSum > 0.8 * negativeP;
    const bool notMuonPair = negativeClusterSumLab > 1 or positiveClusterSumLab > 1;
    const double highp = std::max(negativeP, positiveP);
    const double lowp = std::min(negativeP, positiveP);
    const bool lowEdep = negativeClusterSumLab < 0.5 and positiveClusterSumLab < 0.5;
 
    //..Select two photon fusion lepton pairs
    if (calculationResult["maximumPCMS"] < 2 and dphi > 160 and (pmissTheta < 25. or pmissTheta > 155.)) {
      calculationResult["eexxSelect"] = 1;
      if (electronEP) {
        calculationResult["eeee"] = 1;
      } else {
        calculationResult["eemm"] = 1;
      }
    }
 
    //..Veto two photon fusion lepton pairs
    if ((pmissTheta < 20. or pmissTheta > 160.) and
        ((calculationResult["maximumPCMS"] < 1.2 and dphi > 150.) or
         (calculationResult["maximumPCMS"] < 2. and 175. < dphi))) {
      calculationResult["eexx"] = 1;
    }
 
    //..Radiative Bhabhas with missing momentum in acceptance
    if (negativeP > 1. and pmissTheta > 10. and pmissTheta < 170. and positiveP > 1. and dphi < 170. and pmissp > 1. and electronEP) {
      if (calculationResult["nTrkLoose"] == 2 and calculationResult["nTrkTight"] >= 1) {
        calculationResult["radBhabha"] = 1;
      }
      if (calculationResult["nTrkLooseB"] == 2 and calculationResult["nTrkTightB"] >= 1) {
        calculationResult["radBhabhaB"] = 1;
      }
    }
 
    //..ISR radiative Bhabha with missing momentum down beam pipe
    if (negativeP > 2. and positiveP > 2. and 2 == calculationResult["nTrkLoose"] and
        calculationResult["nTrkTight"] >= 1 and dphi > 175. and
        (pmissTheta < 5. or pmissTheta > 175.) and electronEP) {
      calculationResult["isrRadBhabha"] = 1;
    }
 
    //..Veto Bhabha with hard brem
    if (highp > 4.5 and notMuonPair and pmissp > 1. and (relMissAngle0 < 5. or relMissAngle1 < 5.)) {
      if (calculationResult["nTrkLoose"] == 2) { calculationResult["eeBrem"] = 1;}
      if (calculationResult["nTrkLooseB"] >= 1) { calculationResult["eeBremB"] = 1;}
    }
 
    //..Veto e+e- -> mu+mu-
    if (highp > 4.5 and lowEdep and thetaSum > 175. and thetaSum < 185. and dphi > 175.) {
      if (calculationResult["nTrkLoose"] == 2) {calculationResult["muonPairV"] = 1;}
      if (calculationResult["nTrkLooseB"] == 2) {calculationResult["muonPairVB"] = 1;}
    }
 
    //..Select e+e- -> mu+mu-
    if (highp > 3. and lowp > 2.5 and dphi > 165. and
        ((negativeClusterSumLab > 0. and negativeClusterSumLab < 1.) or
         (positiveClusterSumLab > 0. and positiveClusterSumLab < 1.))) {
      calculationResult["selectmumu"] = 1;
    }
  }
 
  //..Filters and vetoes using two maximum-energy clusters
  if (selectedClusters.size() >= 2) {
    const SelectedECLCluster& firstCluster = selectedClusters[0];
    const SelectedECLCluster& secondCluster = selectedClusters[1];
 
    double dphi = std::abs(firstCluster.p4CMS.Phi() - secondCluster.p4CMS.Phi()) * TMath::RadToDeg();
    if (dphi > 180) {
      dphi = 360 - dphi;
    }
    double thetaSum = (firstCluster.p4CMS.Theta() + secondCluster.p4CMS.Theta()) * TMath::RadToDeg();
    double dthetaSum = std::abs(thetaSum - 180);
 
    //..Quantities for two-photon fusion triggers
    calculationResult["dphiCmsClust"] = dphi;
    for (int ic = 0; ic < 2; ic++) {
      const double thetaLab = selectedClusters[ic].p4Lab.Theta() * TMath::RadToDeg();
      const bool isInAcceptance = 17. < thetaLab and thetaLab < 150.;
      const ECLCluster* cluster = selectedClusters[ic].cluster;
      const double zmva = cluster->getZernikeMVA();
      const bool photon = zmva > 0.5 and not selectedClusters[ic].isTrack;
      if (isInAcceptance and photon) {calculationResult["nMaxEPhotonAcc"] += 1;}
    }
 
    const double firstEnergy = firstCluster.p4CMS.E();
    const double secondEnergy = secondCluster.p4CMS.E();
 
    const bool highEnergetic = firstEnergy > 3 and secondEnergy > 3 and (firstEnergy > 4.5 or secondEnergy > 4.5);
 
    if (dphi > 160 and dphi < 178 and dthetaSum < 15 and highEnergetic) {
      calculationResult["ee2clst"] = 1;
    }
 
    if (dphi > 178 and dthetaSum < 15 and highEnergetic) {
      calculationResult["gg2clst"] = 1;
    }
 
    if ((calculationResult["ee2clst"] == 1 or calculationResult["gg2clst"] == 1) and
        calculationResult["ee1leg"] == 1) {
      calculationResult["ee1leg1clst"] = 1;
    }
 
    const double Elab0 = firstCluster.p4Lab.E();
    const double Elab1 = secondCluster.p4Lab.E();
 
    // gg and mumu accept triggers using ECL
    if (firstEnergy > 2 and secondEnergy > 2) {
      const double thetaLab0 = firstCluster.p4Lab.Theta() * TMath::RadToDeg();
      const double thetaLab1 = secondCluster.p4Lab.Theta() * TMath::RadToDeg();
 
      const bool barrel0 = 32. < thetaLab0 and thetaLab0 < 130.;
      const bool barrel1 = 32. < thetaLab1 and thetaLab1 < 130.;
      const bool oneClustersAbove4 = firstEnergy > 4 or secondEnergy > 4;
      const bool oneIsNeutral = not firstCluster.isTrack or not secondCluster.isTrack;
      const bool bothAreNeutral = not firstCluster.isTrack and not secondCluster.isTrack;
      const bool oneIsBarrel = barrel0 or barrel1;
      const bool dphiCutExtraLoose = dphi > 175;
      const bool dphiCutLoose = dphi > 177;
      const bool dphiCutTight = dphi > 177.5;
 
      if (dphiCutExtraLoose and oneIsNeutral and oneIsBarrel) {
        calculationResult["ggBarrelVL"] = 1;
      }
      if (oneClustersAbove4 and dphiCutLoose and oneIsNeutral and oneIsBarrel) {
        calculationResult["ggBarrelLoose"] = 1;
      }
      if (oneClustersAbove4 and dphiCutTight and bothAreNeutral and oneIsBarrel) {
        calculationResult["ggBarrelTight"] = 1;
      }
      if (dphiCutExtraLoose and oneIsNeutral and not oneIsBarrel) {
        calculationResult["ggEndcapVL"] = 1;
      }
      if (oneClustersAbove4 and dphiCutLoose and oneIsNeutral and not oneIsBarrel) {
        calculationResult["ggEndcapLoose"] = 1;
      }
      if (oneClustersAbove4 and dphiCutTight and bothAreNeutral and not oneIsBarrel) {
        calculationResult["ggEndcapTight"] = 1;
      }
    }
 
    const double minEnergy = std::min(Elab0, Elab1);
    const double maxEnergy = std::max(Elab0, Elab1);
    if (dphi > 155 and thetaSum > 165 and thetaSum < 195 and minEnergy > 0.15 and minEnergy < 0.5 and
        maxEnergy > 0.15 and maxEnergy < 0.5) {
      calculationResult["muonPairECL"] = 1;
    }
 
    //..diPhoton line
    const double thetaLab0 = firstCluster.p4Lab.Theta() * TMath::RadToDeg();
    const double thetaLab1 = secondCluster.p4Lab.Theta() * TMath::RadToDeg();
    const bool inHieRegion0 = thetaLab0 > 26. and thetaLab0 < 130.;
    const bool inHieRegion1 = thetaLab1 > 26. and thetaLab1 < 130.;
    const bool firstIsNeutral = not firstCluster.isTrack;
    const bool secondIsNeutral = not secondCluster.isTrack;
 
    if (secondEnergy > 0.3 and inHieRegion0 and inHieRegion1 and firstIsNeutral and secondIsNeutral) {
      const ROOT::Math::PxPyPzEVector ggP4CMS = firstCluster.p4CMS + secondCluster.p4CMS;
      if (ggP4CMS.pt() > 1.) {calculationResult["ggHighPt"] = 1;}
    }
 
  } // end of two-clusters lines
 
  // Bhabha accept triggers.
  // Use theta_lab of negative track if available; otherwise cluster.
  double thetaFlatten = 0;
 
  // One leg, one cluster.
  for (short charge : { -1, 1}) {
    const auto& maximumPtTrack = maximumPtTracks.at(charge);
    if (not maximumPtTrack) {
      continue;
    }
 
    if (maximumPtTrack->clusterEnergySumCMS > 1.5) {
      double invMass = 0.;
      double tempFlatten = 0.;
      for (const SelectedECLCluster& cluster : selectedClusters) {
        double tempInvMass = (maximumPtTrack->p4Lab + cluster.p4Lab).M();
        if (tempInvMass > invMass) {
          invMass = tempInvMass;
          if (charge == 1) {
            tempFlatten = cluster.p4Lab.Theta() * TMath::RadToDeg();
          }
        }
      }
      if (charge == -1) {
        tempFlatten = maximumPtTrack->p4Lab.Theta() * TMath::RadToDeg();
      }
      if (invMass > 5.29) {
        calculationResult["selectee1leg1clst"] = 1;
        thetaFlatten = tempFlatten;
      }
    }
  }
 
  // Two legs
  if (maximumPtTracks.at(-1) and maximumPtTracks.at(1)) {
    const MaximumPtTrack& negativeTrack = *maximumPtTracks.at(-1);
    const MaximumPtTrack& positiveTrack = *maximumPtTracks.at(1);
    const double invMass = (negativeTrack.p4Lab + positiveTrack.p4Lab).M();
    if (invMass > 5.29 and (negativeTrack.clusterEnergySumCMS > 1.5 or positiveTrack.clusterEnergySumCMS > 1.5)) {
      calculationResult["selectee1leg1trk"] = 1;
    }
 
    thetaFlatten = negativeTrack.p4Lab.Theta() * TMath::RadToDeg();
 
    // Two tracks but (exactly) 1 high energy cluster
    const bool missNegClust = positiveTrack.clusterEnergySumCMS > 4.5 and negativeTrack.clusterEnergySumCMS < 1.;
    const bool missPosClust = negativeTrack.clusterEnergySumCMS > 4.5 and positiveTrack.clusterEnergySumCMS < 1.;
    if ((invMass > 9.) and (missNegClust or missPosClust)) {
      calculationResult["eeOneClust"] = 1;
    }
  }
 
  if (calculationResult["selectee1leg1trk"] == 1 or calculationResult["selectee1leg1clst"] == 1) {
    for (int iflat = 0; iflat < 9; iflat++) {
      const std::string& eeFlatName = "eeFlat" + std::to_string(iflat);
      calculationResult[eeFlatName] =
        thetaFlatten >= flatBoundaries[iflat] and thetaFlatten < flatBoundaries[iflat + 1];
      if (calculationResult[eeFlatName]) {
        calculationResult["selectee"] = 1;
      }
    }
  }
 
  // Single tag pi0 / eta dedicated lines
  if (calculationResult["nTrkLoose"] == 1 and calculationResult["maximumPCMS"] > 0.8 and selectedClusters.size() >= 2) {
 
    decltype(selectedClusters) selectedSingleTagClusters(selectedClusters.size());
    auto lastItem = std::copy_if(selectedClusters.begin(), selectedClusters.end(), selectedSingleTagClusters.begin(),
    [](auto & cluster) {
      const bool isNeutralCluster = not cluster.isTrack;
      const bool hasEnoughEnergy = cluster.energyLab > 0.1;
      const double clusterThetaLab = cluster.p4Lab.Theta() * TMath::RadToDeg();
      const bool isInAcceptance = 17 < clusterThetaLab and clusterThetaLab < 150.;
      return isNeutralCluster and hasEnoughEnergy and isInAcceptance;
    });
    selectedSingleTagClusters.resize(std::distance(selectedSingleTagClusters.begin(), lastItem));
 
    if (selectedSingleTagClusters.size() >= 2) {  // One track and at least two clusters are found
 
      const auto& track = maximumPtTracks.at(-1) ? *maximumPtTracks.at(-1) : *maximumPtTracks.at(1);
      // in real signal, the pi0 decay daughters are always the two most-energetic neutral clusters.
      const auto& firstCluster = selectedSingleTagClusters[0];
      const auto& secondCluster = selectedSingleTagClusters[1];
 
      const ROOT::Math::PxPyPzEVector trackP4CMS = track.p4CMS;
      const ROOT::Math::PxPyPzEVector pi0P4CMS = firstCluster.p4CMS + secondCluster.p4CMS;
 
      const bool passPi0ECMS = pi0P4CMS.E() > 1. and pi0P4CMS.E() < 0.525 * p4ofCOM.M();
      const double thetaSumCMS = (pi0P4CMS.Theta() + trackP4CMS.Theta()) * TMath::RadToDeg();
      const bool passThetaSum = thetaSumCMS < 170. or thetaSumCMS > 190.;
 
      double dphiCMS = std::abs(trackP4CMS.Phi() - pi0P4CMS.Phi()) * TMath::RadToDeg();
      if (dphiCMS > 180) {
        dphiCMS = 360 - dphiCMS;
      }
      const bool passdPhi = dphiCMS > 160.;
 
      if (passPi0ECMS and passThetaSum and passdPhi and pi0P4CMS.M() < 0.7) {
        calculationResult["singleTagLowMass"] = 1;
      } else if (passPi0ECMS and passThetaSum and passdPhi and pi0P4CMS.M() > 0.7) {
        calculationResult["singleTagHighMass"] = 1;
      }
    }
  }
 
  //..Updated to use new track definitions
  if (calculationResult["nTrkLooseB"] == 1 and calculationResult["maximumPCMSB"] > 0.8 and selectedClusters.size() >= 2) {
 
    decltype(selectedClusters) selectedSingleTagClusters(selectedClusters.size());
    auto lastItem = std::copy_if(selectedClusters.begin(), selectedClusters.end(), selectedSingleTagClusters.begin(),
    [](auto & cluster) {
      const bool isNeutralCluster = not cluster.isTrack;
      const bool hasEnoughEnergy = cluster.energyLab > 0.1;
      const double clusterThetaLab = cluster.p4Lab.Theta() * TMath::RadToDeg();
      const bool isInAcceptance = 17 < clusterThetaLab and clusterThetaLab < 150.;
      return isNeutralCluster and hasEnoughEnergy and isInAcceptance;
    });
    selectedSingleTagClusters.resize(std::distance(selectedSingleTagClusters.begin(), lastItem));
 
    if (selectedSingleTagClusters.size() >= 2) {  // One track and at least two clusters are found
 
      const auto& track = maximumPtTracks.at(-1) ? *maximumPtTracks.at(-1) : *maximumPtTracks.at(1);
      // in real signal, the pi0 decay daughters are always the two most-energetic neutral clusters.
      const auto& firstCluster = selectedSingleTagClusters[0];
      const auto& secondCluster = selectedSingleTagClusters[1];
 
      const ROOT::Math::PxPyPzEVector trackP4CMS = track.p4CMS;
      const ROOT::Math::PxPyPzEVector pi0P4CMS = firstCluster.p4CMS + secondCluster.p4CMS;
 
      const bool passPi0ECMS = pi0P4CMS.E() > 1. and pi0P4CMS.E() < 0.525 * p4ofCOM.M();
      const double thetaSumCMS = (pi0P4CMS.Theta() + trackP4CMS.Theta()) * TMath::RadToDeg();
      const bool passThetaSum = thetaSumCMS < 170. or thetaSumCMS > 190.;
 
      double dphiCMS = std::abs(trackP4CMS.Phi() - pi0P4CMS.Phi()) * TMath::RadToDeg();
      if (dphiCMS > 180) {
        dphiCMS = 360 - dphiCMS;
      }
      const bool passdPhi = dphiCMS > 160.;
 
      if (passPi0ECMS and passThetaSum and passdPhi and pi0P4CMS.M() < 0.7) {
        calculationResult["singleTagLowMassB"] = 1;
      } else if (passPi0ECMS and passThetaSum and passdPhi and pi0P4CMS.M() > 0.7) {
        calculationResult["singleTagHighMassB"] = 1;
      }
    }
  }
 
  //..Cosmic selection. Need exactly two tracks.
  if (m_tracks.getEntries() == 2) {
 
    const auto negTrack = maximumPtTracksWithoutZCut.at(-1);
    const auto posTrack = maximumPtTracksWithoutZCut.at(1);
 
    if (negTrack and posTrack) {
 
      const double maxNegpT = negTrack->pT;
      const double maxPospT = posTrack->pT;
      const double maxClusterENeg = negTrack->clusterEnergySumLab;
      const double maxClusterEPos = posTrack->clusterEnergySumLab;
 
      const ROOT::Math::PxPyPzEVector& momentumLabNeg(negTrack->p4Lab);
      const ROOT::Math::PxPyPzEVector& momentumLabPos(posTrack->p4Lab);
 
      const double& z0Neg = negTrack->track->getTrackFitResultWithClosestMass(Const::pion)->getZ0();
      const double& d0Neg = negTrack->track->getTrackFitResultWithClosestMass(Const::pion)->getD0();
      const double& z0Pos = posTrack->track->getTrackFitResultWithClosestMass(Const::pion)->getZ0();
      const double& d0Pos = posTrack->track->getTrackFitResultWithClosestMass(Const::pion)->getD0();
 
      // Select cosmic using these tracks
      const bool goodMagneticRegion = (z0Neg<m_goodMagneticRegionZ0 or abs(d0Neg)>m_goodMagneticRegionD0)
                                      and (z0Pos<m_goodMagneticRegionZ0 or abs(d0Pos)>m_goodMagneticRegionD0);
      if (maxNegpT > m_cosmicMinPt and maxPospT > m_cosmicMinPt and maxClusterENeg < m_cosmicMaxClusterEnergy
          and maxClusterEPos < m_cosmicMaxClusterEnergy and goodMagneticRegion) {
        double dphiLab = std::abs(momentumLabNeg.Phi() - momentumLabPos.Phi()) * TMath::RadToDeg();
        if (dphiLab > 180) {
          dphiLab = 360 - dphiLab;
        }
 
        const double thetaSumLab = (momentumLabNeg.Theta() + momentumLabPos.Theta()) * TMath::RadToDeg();
 
        constexpr double phiBackToBackTolerance = 2.;
        constexpr double thetaBackToBackTolerance = 2.;
        if ((180 - dphiLab) < phiBackToBackTolerance and std::abs(180 - thetaSumLab) < thetaBackToBackTolerance) {
          calculationResult["cosmic"] = 1;
        }
      }
    }
  }
 
  //..Displaced vertex
  // See https://indico.belle2.org/event/8973/ and references therein
  if (maximumPtTracksWithoutZCut.at(-1) and maximumPtTracksWithoutZCut.at(1)) {
 
    //..Make particles of the two highest pt tracks (without IP cut)
    const auto nTrack = maximumPtTracksWithoutZCut.at(-1)->track;
    Particle* nParticle = new Particle(nTrack, Const::pion);
 
    const auto pTrack = maximumPtTracksWithoutZCut.at(1)->track;
    Particle* pParticle = new Particle(pTrack, Const::pion);
 
    //..Make a vertex of these two
    Belle2::analysis::VertexFitKFit* vertexFit = new Belle2::analysis::VertexFitKFit();
    vertexFit->addParticle(nParticle);
    vertexFit->addParticle(pParticle);
    vertexFit->doFit();
 
    //..Vertex properties
    const double chisq = vertexFit->getCHIsq();
    const int ndf = vertexFit->getNDF();
    const double vertexProb = TMath::Prob(chisq, ndf);
    const auto vertexLocation = vertexFit->getVertex();
    const double vertexXY = vertexLocation.perp();
    const double vertexTheta = vertexLocation.theta() * TMath::RadToDeg();
 
    //..Angular differance of two tracks to reject cosmics
    //  Tolerance could be reduced from 10 deg to 2 deg if needed for physics reasons,
    //  for a 5% increase in the rate of selected displaced vertex triggers.
    //  See https://gitlab.desy.de/belle2/software/basf2/-/merge_requests/1867
    const ROOT::Math::PxPyPzEVector& momentumLabNeg(maximumPtTracksWithoutZCut.at(-1)->p4Lab);
    const ROOT::Math::PxPyPzEVector& momentumLabPos(maximumPtTracksWithoutZCut.at(1)->p4Lab);
    const double thetaSumLab = (momentumLabNeg.Theta() + momentumLabPos.Theta()) * TMath::RadToDeg();
    double dPhiLab = std::abs(momentumLabNeg.Phi() - momentumLabPos.Phi()) * TMath::RadToDeg();
    if (dPhiLab > 180) {
      dPhiLab = 360 - dPhiLab;
    }
    const double backToBackTolerance = 10.; // degrees
    const bool backToBackLab = std::abs(thetaSumLab - 180.) < backToBackTolerance and std::abs(dPhiLab - 180.) < backToBackTolerance;
 
    //..Select a displaced vertex
    const double minProbChiVertex = 0.005; // minimum probability chi square. Many backgrounds have bad chi sq.
    const double minXYVertex = 3.; // minimum xy of vertex (cm). Should pass track filters below this.
    const double maxXYVertex = 60.; // maximum xy. Insufficient CDC for good reconstruction beyond this.
    const double minThetaVertex = 30.; // Large Bhabha background at low angles.
    const double maxThetaVertex = 120.; // Large Bhabha background at low angles.
    if (vertexProb > minProbChiVertex and vertexXY > minXYVertex and vertexXY < maxXYVertex and vertexTheta > minThetaVertex
        and vertexTheta < maxThetaVertex
        and not backToBackLab) {calculationResult["displacedVertex"] = 1;}
 
    //..Clean up
    delete nParticle;
    delete pParticle;
    delete vertexFit;
 
  }
 
}