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SUSY Searches in Trilepton Final States at the LHC

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

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SUSY Searches in Trilepton Final States at the LHC

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  1. SUSY Searches in Trilepton Final States at the LHC Martin Niegel University of Karlsruhe for the ATLAS & CMS Collaborations

  2. Outline • Trilepton channel studied in ATLAS & CMS with full and fast detector simulations • Benchmark points for detailed analysis • Exclusive Searches with direct Gaugino production:Neutralino-Chargino (golden channel) χ20χ1±→3l + no jets + MET SM equivalent : ZW → 3l +MET • Inclusive Search: any decay originating from SUSY particles that gives 3l+Njets+MET SUSY07 Karlsruhe

  3. Total SUSY cross section fp Motivation • Total SUSY cross sections strong function of m1/2 • Main channels: gluinos production squarks/sleptons production gauginos production • Gaugino production dominant at focus point region (large m0) [pb] Contribution of gauginos 90% ~0.1pb 20% CMS CMS ~100pb SUSY07 Karlsruhe

  4. Mllmax= m20-m10 Minvmax= sqrt((m220-m2~l)(m2~l-m210)/m2~l ) Trileptons from Neutralino-Chargino Dilepton invariant mass 3 body: CMS Fast sim. BR(χ20)x2l CMS 2 body: CMS Fast sim. BR(χ20)x2l CMS SUSY07 Karlsruhe

  5. CMS A0=0, tanβ=50 0.01pb Higgs NO EWSB 0.1pb 0.2pb CMS benchmark point LM9 Trilepton Cross Section Cross section of neutralino-chargino production x branching ratio to 3l Excluded by LEP SUSY07 Karlsruhe

  6. Trilepton Backgrounds SUSY07 Karlsruhe

  7. Pt of first muon CMS Z/γ*jets ttbar 3l Reconstruction of Leptons Lepton has to be isolated from jets Isolation by tracks: ΣPt< 1.5 GeVinΔR<0.3 Isolation by calo (muons): ΣEt< 5 GeVinΔR<0.3 Electron id by likelihood: E/P , H/E , E3x3/E5x5, Δη,σηη Pt of third muon CMS ZW Z/γ*jets SUSY07 Karlsruhe

  8. Reconstruction of JET/MET Jet multiplicity shapes Signal hassmall MET due to light LSP and small mass difference Δm(χ20-χ10) CMS Missing ET CMS • 1/3 of signal evts have ISR • Large jet multiplicity for ttbar and Z+jets reduce background SUSY07 Karlsruhe

  9. Different possibilities: All OSSF combinations-> largest significance high Pt pairs. good efficiency to the MC tagged pairs. low Pt pairs difficult – moves Z peak to the signal region DFOS related to the combinatorial bkg., useless here Invariant Mass Reconstruction CMS full simulation CMS SUSY07 Karlsruhe

  10. Selection Cuts Trigger selection (LV1): (TrileptonsM0=1450,M1/2=175,tanβ=50)) dimuon stream (Pt > 3 GeV) : ~75% dielectron stream (Pt > 17 GeV): ~25% • Offline Selection: • No central Jets withEt > 30 GeV,η< 2.4 • Two isolated opposite sign same flavour (OSSF)leptons inη < 2.4with:Pt of muons > 10 GeV Pt of electrons > 17 GeV • Invariant mass of leptons below Z-PeakMll < 75 GeV • Third isolated leptonPt > 10 GeV, η < 2.4 SUSY07 Karlsruhe

  11. Mll result plots for LM9 (30fb-1) CMS fast sim. CMS 2e+l All OSSF leptons (e,μ) CMS 2μ+l CMS SUSY07 Karlsruhe

  12. Z-Peak CMS Z-Peak Higgs No EWSB No EWSB Excluded by LEP Excluded by LEP 5σ-Discovery reach (30fb-1) CMS fast simulation CMS Higgs LM9 [CMS] : O(30fb-1) Focus Point [ATLAS] : O(100 fb-1) (M0=1450,M1/2=175,tanβ=50) (M0=3550,M1/2=300,tanβ=10) Ntrilepton/fb-1: 130Ntrilepton/fb-1: 30 SUSY07 Karlsruhe

  13. Signal only SU3 ATLAS preliminary theoretical endpoint at ~ 100 GeV OSSF Dilepton Edge (GeV) Inclusive Search in Trileptons Inclusive = any decay originating from SUSY particles that gives three leptons (+jets) in the final state Backgrounds: ttbar, ZW, ZZ, Zb, Zγ, WW 5σ-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) SUSY07 Karlsruhe

  14. Outlook • The 5σ trilepton signal from direct neutralino chargino production can be observed for m1/2<200 GeV, m0>1000 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 SUSY07 Karlsruhe

  15. BACKUP SLIDES SUSY07 Karlsruhe

  16. Cut Flow Table CMS SUSY07 Karlsruhe

  17. MET resolution CMS MET2= (3.8)2+ (0.97 ET )2 + (0.012ET)2 Backup: MET SUSY07 Karlsruhe

  18. Excluded Backup: TEVATRON SUSY07 Karlsruhe

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