SUSY Searches in Trilepton Final States at the LHC

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SUSY Searches in Trilepton Final States at the LHC. Martin Niegel University of Karlsruhe for the ATLAS & CMS Collaborations. Outline. Trilepton channel studied in ATLAS & CMS with full and fast detector simulations Benchmark points for detailed analysis - PowerPoint PPT Presentation

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  • SUSY Searches in Trilepton Final States at the LHC Martin Niegel University of Karlsruhefor the ATLAS & CMS Collaborations

    SUSY07 Karlsruhe

  • OutlineTrilepton channel studied in ATLAS & CMS with full and fast detector simulationsBenchmark points for detailed analysis

    Exclusive Searches with direct Gaugino production:Neutralino-Chargino (golden channel)201 3l + no jets + METSM equivalent : ZW 3l +METInclusive Search: any decay originating from SUSY particles that gives 3l+Njets +MET

    M0M1/2tanA0sign [pb]SU2 (ATLAS)3550300100+14.5Focus pointSU3 (ATLAS)1003006-300+118.6Bulk region LM9 (CMS)1450175500+124.6Light neutralinoSU4 (ATLAS)20016010-400+1262Low mass SUSY

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  • Motivation Contribution of gauginos20%90%~0.1pb~100pbTotal SUSY cross sections strong function of m1/2Main channels: gluinos production squarks/sleptons production gauginos productionGaugino production dominant at focus point region (large m0)CMSCMS [pb]

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  • Trileptons from Neutralino-Chargino3 body:2 body:Dilepton invariant massCMSCMSCMSBR(20)x2lBR(20)x2lCMSFast sim.Fast sim.

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  • Trilepton Cross SectionExcluded by LEPCross section of neutralino-chargino production x branching ratio to 3l

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  • Trilepton Backgrounds

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  • Reconstruction of LeptonsLepton has to be isolated from jetsIsolation by tracks: Pt< 1.5 GeVin R
  • Reconstruction of JET/METSignal has small MET due to light LSP and small mass difference m(20-10) 1/3 of signal evts have ISRLarge jet multiplicity for ttbar and Z+jets reduce background

    CMSJet multiplicity shapesMissing ETCMS

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  • Invariant Mass ReconstructionCMSCMS full simulation

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  • Selection CutsOffline Selection:No central Jets with Et > 30 GeV, < 2.4Two isolated opposite sign same flavour (OSSF) leptons in < 2.4 with: Pt of muons > 10 GeVPt of electrons > 17 GeVInvariant mass of leptons below Z-Peak Mll < 75 GeV Third isolated lepton Pt > 10 GeV, < 2.4

    Trigger selection (LV1): (Trileptons M0=1450,M1/2=175,tan=50)) dimuon stream (Pt > 3 GeV) : ~75% dielectron stream (Pt > 17 GeV): ~25%

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  • Mll result plots for LM9 (30fb-1)2e+l2+lAll OSSF leptons (e,)CMSCMSCMSCMS fast sim.

    final stateNev signalNev bkgs/sqrt(s+b)2e+l515012.32+l17910165.6All OSSF29715176.6

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  • 5-Discovery reach (30fb-1) CMS fast simulationCMSHiggsLM9 [CMS] : O(30fb-1) Focus Point [ATLAS] : O(100 fb-1)(M0=1450,M1/2=175,tan=50) (M0=3550,M1/2=300,tan=10)Ntrilepton/fb-1: 130 Ntrilepton/fb-1: 30

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  • Inclusive Search in TrileptonsInclusive = any decay originating from SUSY particles that gives three leptons (+jets) in the final state5-Discovery reach: [ATLAS] O(10-15fb-1) [SU2]:(M0=3550,M1/2=300,tb=10)O(1-2fb-1) [SU3]:(M0=100,M1/2=300,tb=6)O(100-150pb-1) [SU4]:(M0=200,M1/2=160,tb=10)Backgrounds: ttbar, ZW, ZZ, Zb, Z, WW

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  • OutlookThe 5 trilepton signal from direct neutralino chargino production can be observed for m1/21000 GeV in mSUGRA mass plane

    The discovery reach is limited by isolation efficiency of leptons and low missing ET for the signal

    Observation of trilepton signal from gauginos production is complimentary to gluino (squarks) cascade decays and allows to identify region in mSUGRA parameter space

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  • BACKUP SLIDES

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  • Cut Flow Table CMS

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  • Backup: MET

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  • Backup: TEVATRON

    DatasetLHC [pb]Tev [pb]Trilepton6.30.56Zjets(mll>10)~70000~6600WZ16.71.27

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