Adding tracks compatible with a Xi to lost tracks

- add to lostTracks tracks consistent with coming from a Xi candidate decaying to LambdaPi
- adding a flag to turn on the slection

Author: AdrianoDee

PhysicsTools/PatAlgos/plugins/PATLostTracks.cc

@@ -12,6 +12,8 @@
 #include "FWCore/ParameterSet/interface/ParameterSet.h"
 #include "CommonTools/Utils/interface/StringCutObjectSelector.h"
 
+#include "TLorentzVector.h"
+
 namespace {
   bool passesQuality(const reco::Track& trk, const std::vector<reco::TrackBase::TrackQuality>& allowedQuals) {
     for (const auto& qual : allowedQuals) {
@@ -68,6 +70,8 @@ namespace pat {
     const double maxDxyForNotReconstructedPrimary_;
     const double maxDxySigForNotReconstructedPrimary_;
     const bool useLegacySetup_;
+    const bool xiSelection_;
+    const double xiMassCut_;
   };
 }  // namespace pat
 
@@ -100,7 +104,9 @@ pat::PATLostTracks::PATLostTracks(const edm::ParameterSet& iConfig)
                                             .getParameter<double>("maxDxyForNotReconstructedPrimary")),
       maxDxySigForNotReconstructedPrimary_(iConfig.getParameter<edm::ParameterSet>("pvAssignment")
                                                .getParameter<double>("maxDxySigForNotReconstructedPrimary")),
-      useLegacySetup_(iConfig.getParameter<bool>("useLegacySetup")) {
+      useLegacySetup_(iConfig.getParameter<bool>("useLegacySetup")),
+      xiSelection_(iConfig.getParameter<double>("xiSelection")),
+      xiMassCut_(iConfig.getParameter<double>("xiMassCut")) {
   std::vector<std::string> trkQuals(iConfig.getParameter<std::vector<std::string>>("qualsToAutoAccept"));
   std::transform(
       trkQuals.begin(), trkQuals.end(), std::back_inserter(qualsToAutoAccept_), reco::TrackBase::qualityByName);
@@ -189,11 +195,27 @@ void pat::PATLostTracks::produce(edm::StreamID, edm::Event& iEvent, const edm::E
         trkStatus[key] = TrkStatus::VTX;
     }
   }
-  for (const auto& v0 : *lambdas) {
-    for (size_t dIdx = 0; dIdx < v0.numberOfDaughters(); dIdx++) {
-      size_t key = (dynamic_cast<const reco::RecoChargedCandidate*>(v0.daughter(dIdx)))->track().key();
-      if (trkStatus[key] == TrkStatus::NOTUSED)
-        trkStatus[key] = TrkStatus::VTX;
+  for (const auto& v0 : *lambdas){
+    double protonCharge = 0;
+    for(size_t dIdx=0;dIdx<v0.numberOfDaughters(); dIdx++){
+      size_t key= (dynamic_cast<const reco::RecoChargedCandidate*>(v0.daughter(dIdx)))->track().key();
+      if(trkStatus[key]==TrkStatus::NOTUSED)  trkStatus[key]=TrkStatus::VTX;
+      protonCharge += v0.daughter(dIdx)->charge() * v0.daughter(dIdx)->momentum().mag2();
+    }
+    if (xiSelection_)
+    {
+      // selecting potential Xi- -> Lambda pi candidates
+      TLorentzVector p4Lambda;
+      p4Lambda.SetPtEtaPhiM(v0.pt(),v0.eta(),v0.phi(), v0.mass());
+      for(unsigned int trkIndx=0; trkIndx < tracks->size(); trkIndx++){
+        reco::TrackRef trk(tracks,trkIndx);
+        if ((*trk).charge() * protonCharge < 0) continue;
+        TLorentzVector p4pi;
+        p4pi.SetPtEtaPhiM((*trk).pt(),(*trk).eta(),(*trk).phi(), 0.13957061);
+        if ((p4Lambda+p4pi).M() < xiMassCut_){ // selecting potential Xi- candidates
+          if(trkStatus[trkIndx]==TrkStatus::NOTUSED) trkStatus[trkIndx]=TrkStatus::VTX;
+        }
+      }
     }
   }
   std::vector<int> mapping(tracks->size(), -1);

PhysicsTools/PatAlgos/python/slimming/lostTracks_cfi.py

@@ -22,7 +22,9 @@
     minPtToStoreLowQualityProps = cms.double(0.0),
     passThroughCut = cms.string("pt>2"),
     pvAssignment = primaryVertexAssociation.assignment,
-    useLegacySetup = cms.bool(False) #When True: check only if track used to fit vertex[0] and do not store track detailed info for Pt between 0.5 and minPtToStoreProps GeV
+    useLegacySetup = cms.bool(False), #When True: check only if track used to fit vertex[0] and do not store track detailed info for Pt between 0.5 and minPtToStoreProps GeV
+    xiSelection = cms.bool(True),
+    xiMassCut = cms.bool(1.6) 
 )
 from Configuration.Eras.Modifier_phase1Pixel_cff import phase1Pixel
 phase1Pixel.toModify(lostTracks, covarianceVersion =1 )