Modified HEEP ID for Z’ SUSY Search Norbert Neumeister, Hwidong Yoo Purdue University Identification e/g meeting January 29, 2014

Outline Introduction Signal modeling Event selection: HEEP id Merged electron Modification of HEEP id variables Electron isolation

Introduction Non-typical Z’ search A baryonic Z´ resonance model 4 leptons in the final state μμμμ, μμμe, μμee, μeee, eeee V. Barger, H.S. Lee, Phys. Rev. D 85, 055030 (2012) http://prd.aps.org/abstract/PRD/v85/i5/e055030 Several presentations in EXO non-hadronic meetings In the talk at Dec. we fully discussed the electron id https://indico.cern.ch/conferenceDisplay.py?confId=283543 Asked to discuss details of the modified HEEP id in E/g meetings that we have used in this search

Signal Modeling Z’ → 4 leptons Generator: CalcHep 3.4.1 + Pythia Tree level matrix element (ME) calculation by CalcHEP Model files provided by authors of theory paper Generate 10 mass bins (12000 events each) for expected limit calculations M = 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000 GeV Five channels: μμμμ, μμμe, μμee, μeee, eeee Simulation and reconstruction Use Full-Sim: https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideSimulation PV smearing, pile-up mixing, L1/HLT emulation, physics object reconstructions CMSSW_5_3_4 with Summer12 S10 Pile-up scenario Apply pT > 45 GeV (leading), pT > 30 GeV (sub-leading) with |eta| < 2.4 Performance is based on the signal mc samples

Event Selection: HEEP ID Apply HEEP id for all electrons in each channel https://twiki.cern.ch/twiki/bin/viewauth/CMS/HEEPElectronID Use modified HEEP isolation https://twiki.cern.ch/twiki/bin/viewauth/CMS/BoostedZToEEModIso Modify the HEEP id to improve the efficiency for boosted electrons Same feature as for muon, but in electron case, the boosted two electrons are merged as a single electron in the reconstruction of the ECAL supercluster Modified HEEP id by boosted Z→ee analysis doesn’t work in our analysis Additionally there are several id variables to introduce inefficiency for such boosted electrons Z’, M = 3 TeV

Boosted Z→ee AN2012-168 for boosted Z→ee analysis Inefficiency starts in current standard electron reconstruction in barrel and endcap Apply the cut for dEta < 0.07 and dPhi < 0.3 In high mass sample most of electrons are rejected by the cuts in our case AN2012-168

Merged Electron Problem happens in current supercluster algorithm Hybrid algorithm in barrel Fixed bar of 3 or 5 crystals in eta direction Dynamic search in phi direction Fixed 5*5 crystals in endcap In supercluster reconstruction, the ECAL rechits from two electrons are merged as one in many cases if they are close to each other and are reconstructed as a single supercluster Only ECAL rechits used in the supercluster are stored in RECO/AOD format sample. Other rechits are not. There is no way to separate the merged supercluster in order to match to the tracker tracks Therefore, in current standard supercluster algorithm, we can not avoid this merged electron

Merged Electron: Example Event Example event for the merged electron Truth tracks e1: pt = 1162.0 GeV e2: pt = 27.8 GeV e3: pt = 905.9 GeV e4: pt = 284.2 GeV e3+e4 is close to E3 Two reco electrons E1: et =1146.2 GeV E2: et = 32.0 GeV E1 E2 From e4 One reco electron E3: et =1103.4 GeV From e3 Two ECAL rechit towers shown but they are merged in supercluster and the supercluster is used to reconstruct electron Reconstructed E3

Merged Electron ID (1) Although the electrons are merged in the supercluster, a gsfTrack is usually reconstructed for the 2nd electron (that is merged to the 1st electron) Check the dR(gsfTrack, electron) Use gsfTrack with pt > 30 GeV E/p of the merged electron should be larger than 1.0 because the 2nd electron is merged in the supercluster Probability for merged electrons significantly increases for very high pT electrons Apply this algorithm to only very high pT electrons

Merged Electron ID (2) Selection: dR < 0.25 and E/p > 1.5 for electron et > 500 GeV Et < 100 Black: merged electron Red: non-merged electron 100 < Et < 500 500 < Et < 750 750 < Et < 1000 No merged electron, et < 500 GeV Significant contribution from non-merged electron up to E/p 1.5 Et > 1000 Use Z’ signal MC sample with various masses

Modification of HEEP ID: dEtaIn Difference in eta between the tracker position (measured in inner layer) and the eta of the supercluster Sensitive variable for the merged electron HEEP id: 0.005 (EB), 0.007 (EE) Modification: 0.02 for EB and EE Significant contributions above 0.005 in high pT electrons EB EE

Modification of HEEP ID: H/E Ratio of the HCAL energy of the CaloTowers in a cone of radius 0.15 to the electron’s supercluster ECAL energy HEEP id: 0.05 Modification: 0.1 Significant contributions above 0.005 in pT < 1000 GeV EB EE

E(2x5)/E(5x5), E(1x5)/E(5x5) Ratio between supercluster energy (2x5 or 1x5) / 5x5 HEEP id: E(2x5)/E(5x5) > 0.94 or E(1x5)/E(5x5) > 0.83 Drop this variable Electrons with E(1x5)/E(5x5) < 0.83 Significant contribution < 0.94

Electron Isolation Try both original HEEP iso and modified HEEP iso Cut values are same but isolation definitions are different Track iso < 5 GeV ECAL iso + HCAL depth1 iso – 0.28*rho < 2.0 GeV + 0.03 * Et in barrel < 2.5 GeV in endcap, for Et < 50 GeV < 2.5 GeV + 0.03*(Et-50) in endcap, otherwise Both isolations have significant inefficiency in high electron et In origianl HEEP iso, there is strange feature (wiggles) in the high et distribution Modified iso has stable efficiency up to 500 GeV but it is significantly decreasing in the higher et region.

Difference of Isolation Efficiency Tracker isolation is strongly dependent on the Z’ mass This feature is caused that two muons from same mother particle are close to each other by the boost M = 1750 Replace by 4elec M = 3000 M = 750

Iso Efficiency with dR All M = 1750 Replace by 4elec M = 3000 M = 750

Modified HEEP Isolation In the algorithm, we need to apply the HEEP id Need to change cut parameters of HEEP id used in the Thomas’s package, same as what I am using in this analysis Certainly this HEEP id cuts introduce the inefficiency. The feature of strange wiggle is caused by the boost, same as muon Trk Iso still introduces additional inefficiency in high et region Use modified ECAL iso + HCAL depth1 iso Change the factor by 0.05 instead of 0.03 to increase efficiency in high et region

Summary

Back Up

Model 1 SM quark SM leptons 4G quarks 4G leptons U(1)B 1/3 -4 4 lepton Z´ resonance model without having a corresponding lepton pair signal Use generic SUSY framework But B (baryon number) is not preserved in the SUSY framework and proton is unstable Consider gauged B by introducing U(1)B Motivated to protect proton stability in SUSY But in gauging B, additional fermions for anomaly cancellation One possibility: an entire 4G family with B for all quarks Under this condition Proton decay (ΔB = 1) never occurs Z´  ee, μμ, ττ are absent. (no dilepton resonance) Z´  ν4ν4*, where ν42l is possible (4 lepton resonance), where ν4 is the lightest of the 4G states Multilepton Z´ resonance without dilepton resonance is possible with large cross section SM quark SM leptons 4G quarks 4G leptons U(1)B 1/3 -4 ~ ~ ~ ~

Datasets 2012 Dataset SingleMu, DoublePhotonHighPt and MuEG PDs to collect muons, electrons and emu events Use Jan22 ReReco and corresponding golden JSON file Full 2012 dataset: 19.7/fb MC Signal: private production (see next slide) Backgrounds Use Summer12 MC samples DY (Powheg, high mass samples), ttbar, tW/tbarW, dibosons (WW, WZ, ZZ), W+Jets, QCD Full list in next slide

MC Samples Drell-Yan /DYTo**_M_##_TuneZ2star_8TeV_pythia6/Summer12-PU_S7_START52_V9-v1/AODSIM ** = EE or MuMu ## = 20, 200, 500, 800, 1000, 1300, 1600 Diboson /WW_TuneZ2star_8TeV_pythia6_tauola/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM /WZ_TuneZ2star_8TeV_pythia6_tauola/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM /ZZ_TuneZ2star_8TeV_pythia6_tauola/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM ttbar /TT_CT10_TuneZ2star_8TeV-powheg-tauola/Summer12_DR53X-PU_S10_START53_V7A-v2/AODSIM Drell-Yan tautau: /DYToTauTau_M-20_CT10_TuneZ2star_8TeV-powheg-pythia6/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM W+Jets: /WJetsToLNu_TuneZ2Star_8TeV-madgraph-tarball/Summer12-PU_S7_START52_V9-v1/AODSIM QCD MC EMEncriched /QCD_Pt_**_EMEnriched_TuneZ2star_8TeV_pythia6/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM **: 20-30, 30-80, 80-170, 170-250, 250-350, 350 MuEnriched /QCD_Pt-**_MuEnrichedPt5_TuneZ2star_8TeV_pythia6/Summer12_DR53X-PU_S10_START53_V7A-v1/AODSIM **: 20-30, 30-50, 50-80, 80-120, 120-170, 170-300, 300-470, 470-600, 600-800, 800-1000, 1000

HEEP ID Common ecalDriven = 1 H/E < 0.05 |dPhiIn| < 0.06 Inner layer lost hits <= 1 EB E(2x5)/E(5x5) > 0.94 or E(1x5)/E(5x5) > 0.83 |dEtaIn| < 0.005 |dxy| < 0.02 EE |dEtaIn| < 0.007 Sigma_ieta_ieta < 0.03 |dxy| < 0.05 No isolation cuts are applied in our analysis