btau/plugins/HLTDisplacedmumuFilter.cc

0001 #include <iostream>
0002
0003 #include "FWCore/Framework/interface/ESHandle.h"
0004 #include "FWCore/MessageLogger/interface/MessageLogger.h"
0005
0006 #include "DataFormats/Candidate/interface/CandidateFwd.h"
0007 #include "DataFormats/RecoCandidate/interface/RecoCandidate.h"
0008 #include "DataFormats/RecoCandidate/interface/RecoChargedCandidate.h"
0009 #include "DataFormats/RecoCandidate/interface/RecoChargedCandidateFwd.h"
0010 #include "DataFormats/Candidate/interface/Candidate.h"
0011
0012 #include "DataFormats/TrackReco/interface/TrackFwd.h"
0013 #include "DataFormats/TrackReco/interface/Track.h"
0014
0015 #include "DataFormats/VertexReco/interface/Vertex.h"
0016 #include "DataFormats/VertexReco/interface/VertexFwd.h"
0017 #include "DataFormats/Common/interface/RefToBase.h"
0018 #include "DataFormats/HLTReco/interface/TriggerFilterObjectWithRefs.h"
0019 #include "DataFormats/HLTReco/interface/TriggerRefsCollections.h"
0020
0021 #include "DataFormats/BeamSpot/interface/BeamSpot.h"
0022
0023 #include "DataFormats/Math/interface/Error.h"
0024 #include "DataFormats/Math/interface/Point3D.h"
0025 #include "DataFormats/GeometryVector/interface/GlobalPoint.h"
0026 #include "DataFormats/GeometryCommonDetAlgo/interface/GlobalError.h"
0027
0028 #include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
0029
0030 #include "HLTDisplacedmumuFilter.h"
0031 #include "TMath.h"
0032
0033 //
0034 // constructors and destructor
0035 //
0036 HLTDisplacedmumuFilter::HLTDisplacedmumuFilter(const edm::ParameterSet& iConfig)
0037     : HLTFilter(iConfig),
0038       fastAccept_(iConfig.getParameter<bool>("FastAccept")),
0039       minLxySignificance_(iConfig.getParameter<double>("MinLxySignificance")),
0040       maxLxySignificance_(iConfig.getParameter<double>("MaxLxySignificance")),
0041       maxNormalisedChi2_(iConfig.getParameter<double>("MaxNormalisedChi2")),
0042       minVtxProbability_(iConfig.getParameter<double>("MinVtxProbability")),
0043       minCosinePointingAngle_(iConfig.getParameter<double>("MinCosinePointingAngle")),
0044       DisplacedVertexTag_(iConfig.getParameter<edm::InputTag>("DisplacedVertexTag")),
0045       DisplacedVertexToken_(consumes<reco::VertexCollection>(DisplacedVertexTag_)),
0046       beamSpotTag_(iConfig.getParameter<edm::InputTag>("BeamSpotTag")),
0047       beamSpotToken_(consumes<reco::BeamSpot>(beamSpotTag_)),
0048       MuonTag_(iConfig.getParameter<edm::InputTag>("MuonTag")),
0049       MuonToken_(consumes<reco::RecoChargedCandidateCollection>(MuonTag_)) {}
0050
0051 HLTDisplacedmumuFilter::~HLTDisplacedmumuFilter() = default;
0052
0053 void HLTDisplacedmumuFilter::fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
0054   edm::ParameterSetDescription desc;
0055   makeHLTFilterDescription(desc);
0056   desc.add<bool>("FastAccept", false);
0057   desc.add<double>("MinLxySignificance", 0.0);
0058   desc.add<double>("MaxLxySignificance", 0.0);
0059   desc.add<double>("MaxNormalisedChi2", 10.0);
0060   desc.add<double>("MinVtxProbability", 0.0);
0061   desc.add<double>("MinCosinePointingAngle", -2.0);
0062   desc.add<edm::InputTag>("DisplacedVertexTag", edm::InputTag("hltDisplacedmumuVtx"));
0063   desc.add<edm::InputTag>("BeamSpotTag", edm::InputTag("hltOnlineBeamSpot"));
0064   desc.add<edm::InputTag>("MuonTag", edm::InputTag("hltL3MuonCandidates"));
0065   descriptions.add("hltDisplacedmumuFilter", desc);
0066 }
0067
0068 // ------------ method called once each job just before starting event loop  ------------
0069 void HLTDisplacedmumuFilter::beginJob() {}
0070
0071 // ------------ method called once each job just after ending the event loop  ------------
0072 void HLTDisplacedmumuFilter::endJob() {}
0073
0074 // ------------ method called on each new Event  ------------
0075 bool HLTDisplacedmumuFilter::hltFilter(edm::Event& iEvent,
0076                                        const edm::EventSetup& iSetup,
0077                                        trigger::TriggerFilterObjectWithRefs& filterproduct) const {
0078   // get beam spot
0079   reco::BeamSpot vertexBeamSpot;
0080   edm::Handle<reco::BeamSpot> recoBeamSpotHandle;
0081   iEvent.getByToken(beamSpotToken_, recoBeamSpotHandle);
0082   vertexBeamSpot = *recoBeamSpotHandle;
0083
0084   // get displaced vertices
0085   reco::VertexCollection displacedVertexColl;
0086   edm::Handle<reco::VertexCollection> displacedVertexCollHandle;
0087   bool foundVertexColl = iEvent.getByToken(DisplacedVertexToken_, displacedVertexCollHandle);
0088   if (foundVertexColl)
0089     displacedVertexColl = *displacedVertexCollHandle;
0090
0091   // get muon collection
0092   edm::Handle<reco::RecoChargedCandidateCollection> mucands;
0093   iEvent.getByToken(MuonToken_, mucands);
0094
0095   // All HLT filters must create and fill an HLT filter object,
0096   // recording any reconstructed physics objects satisfying (or not)
0097   // this HLT filter, and place it in the Event.
0098
0099   // Ref to Candidate object to be recorded in filter object
0100   reco::RecoChargedCandidateRef ref1;
0101   reco::RecoChargedCandidateRef ref2;
0102
0103   if (saveTags())
0104     filterproduct.addCollectionTag(MuonTag_);
0105
0106   bool triggered = false;
0107
0108   // loop over vertex collection
0109   for (const auto& displacedVertex : displacedVertexColl) {
0110     // check if the vertex actually consists of exactly two muon tracks, throw exception if not
0111     if (displacedVertex.tracksSize() != 2)
0112       throw cms::Exception("BadLogic") << "HLTDisplacedmumuFilter: ERROR: the Jpsi vertex must have exactly two muons "
0113                                           "by definition. It now has n muons = "
0114                                        << displacedVertex.tracksSize() << std::endl;
0115
0116     float normChi2 = displacedVertex.normalizedChi2();
0117     if (normChi2 > maxNormalisedChi2_)
0118       continue;
0119
0120     double vtxProb = 0.0;
0121     if ((displacedVertex.chi2() >= 0.0) && (displacedVertex.ndof() > 0))
0122       vtxProb = TMath::Prob(displacedVertex.chi2(), displacedVertex.ndof());
0123     if (vtxProb < minVtxProbability_)
0124       continue;
0125
0126     // get the two muons from the vertex
0127     auto trackIt = displacedVertex.tracks_begin();
0128     reco::TrackRef vertextkRef1 = (*trackIt).castTo<reco::TrackRef>();
0129     // the second one
0130     trackIt++;
0131     reco::TrackRef vertextkRef2 = (*trackIt).castTo<reco::TrackRef>();
0132
0133     // first find these two tracks in the muon collection
0134     reco::RecoChargedCandidateCollection::const_iterator cand1;
0135     reco::RecoChargedCandidateCollection::const_iterator cand2;
0136
0137     int iFoundRefs = 0;
0138     for (auto cand = mucands->begin(); cand != mucands->end(); cand++) {
0139       reco::TrackRef tkRef = cand->get<reco::TrackRef>();
0140       if (tkRef == vertextkRef1) {
0141         cand1 = cand;
0142         iFoundRefs++;
0143       }
0144       if (tkRef == vertextkRef2) {
0145         cand2 = cand;
0146         iFoundRefs++;
0147       }
0148     }
0149     if (iFoundRefs < 2)
0150       throw cms::Exception("BadLogic") << "HLTDisplacedmumuFilter: ERROR: the muons matched with the Jpsi vertex "
0151                                           "tracks should be at least two by definition."
0152                                        << std::endl;
0153
0154     // calculate two-track transverse momentum
0155     math::XYZVector pperp(cand1->px() + cand2->px(), cand1->py() + cand2->py(), 0.);
0156
0157     const reco::Vertex::Point& vpoint = displacedVertex.position();
0158     //translate to global point, should be improved
0159     GlobalPoint secondaryVertex(vpoint.x(), vpoint.y(), vpoint.z());
0160
0161     reco::Vertex::Error verr = displacedVertex.error();
0162     // translate to global error, should be improved
0163     GlobalError err(verr.At(0, 0), verr.At(1, 0), verr.At(1, 1), verr.At(2, 0), verr.At(2, 1), verr.At(2, 2));
0164
0165     GlobalPoint displacementFromBeamspot(-1 * ((vertexBeamSpot.x0() - secondaryVertex.x()) +
0166                                                (secondaryVertex.z() - vertexBeamSpot.z0()) * vertexBeamSpot.dxdz()),
0167                                          -1 * ((vertexBeamSpot.y0() - secondaryVertex.y()) +
0168                                                (secondaryVertex.z() - vertexBeamSpot.z0()) * vertexBeamSpot.dydz()),
0169                                          0);
0170
0171     float lxy = displacementFromBeamspot.perp();
0172     float lxyerr = sqrt(err.rerr(displacementFromBeamspot));
0173
0174     //calculate the angle between the decay length and the mumu momentum
0175     reco::Vertex::Point vperp(displacementFromBeamspot.x(), displacementFromBeamspot.y(), 0.);
0176
0177     float cosAlpha = vperp.Dot(pperp) / (vperp.R() * pperp.R());
0178
0179     // check thresholds
0180     if (cosAlpha < minCosinePointingAngle_)
0181       continue;
0182     if (minLxySignificance_ > 0. && lxy / lxyerr < minLxySignificance_)
0183       continue;
0184     if (maxLxySignificance_ > 0. && lxy / lxyerr > maxLxySignificance_)
0185       continue;
0186     triggered = true;
0187
0188     // now add the muons that passed to the filter object
0189
0190     ref1 = reco::RecoChargedCandidateRef(
0191         edm::Ref<reco::RecoChargedCandidateCollection>(mucands, distance(mucands->begin(), cand1)));
0192     filterproduct.addObject(trigger::TriggerMuon, ref1);
0193
0194     ref2 = reco::RecoChargedCandidateRef(
0195         edm::Ref<reco::RecoChargedCandidateCollection>(mucands, distance(mucands->begin(), cand2)));
0196     filterproduct.addObject(trigger::TriggerMuon, ref2);
0197   }
0198
0199   LogDebug("HLTDisplacedMumuFilter") << " >>>>> Result of HLTDisplacedMumuFilter is " << triggered << std::endl;
0200
0201   return triggered;
0202 }