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Advanced Physics Research in Higgs and SUSY Models at ATLAS

Explore latest findings in Higgs and SUSY models with detailed analyses like ttH(WW*), SUSY decay, and Compressed-SUSY-2top at ATLAS experiment. Discover insights into particle physics phenomena and potential dark matter sources.

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Advanced Physics Research in Higgs and SUSY Models at ATLAS

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  1. NewPhysicsSearch at ATLAS Yu Bai2, Shan Jin2, Sabine Kraml3, Feng Lu2, Emmanuel Monnier1, LianYou Shan2, Muanza Steve1, Huaqiao Zhang1, Xueyao Zhang4, Zhichao Zhan4,2 ( 1:CPPM, 2:IHEP, 3:LPSC,4:SDU ) F. Lu, FCPPL-3，Lyon/France 2010-4-8

  2. Outline • CSC official result • ttH(WW*) 2L&3L 14TeV Fulsim Analysis • ttH(WW*) 3L 14TeV Fulsim Analysis • ttH extension analysis (work in progress) • SUSY 2top incl. & Excl. 10TeV Fulsim Analysis • SUSY 4top 1L & 0L 10TeV Fastsim Analysis • Further plan F. Lu, FCPPL-3，Lyon/France 2010-4-8

  3. Ndata - Nbkg ttH(HWW)：top YukawaCouplingmeasurement Systematic errors • Nnl ( n=2, 3 ): observed events in ttH-WW* n-lepton final states • L: LHC integrated luminosity • εnl: total efficiency of n-lepton final states • I(MH): the integral over the parton momentum in initial states, propagator of gluon or quark in middle states and lepton/jet phase space in the final states • Cnl: the combination factor of branching of W decays Directly measures: (ttH)*Br(HWW)=Nnl/(LnlCnl) Important to study Higgs property F. Lu, FCPPL-3，Lyon/France

  4. Selection • Basic selection e, mu, C4-jet: |η|<2.5; Pt>15 GeV/c e(Egamma):isEM=0x3FF,author=1,3 mu(StacoMu):IscombinedMuon=1 • Calo Isolation:etcone20<10 GeV • Track Isolation:trkPtmax20<2.0 GeV/c • Cone Isolation:muon:dR(mu,jet)>0.25 electron:dR(e,jet) > 0.2 or dR(e,jet)<0.1 and Eele/Ejet>0.65 ( Remove related jet ) Isolation: Nlepton>=2/3, Njets>=6/4 • Nlep=2/3,Same charge (for 2L) • Zveto:(75,100) (lep Pt> 6GeV/c) • MuonPt> 20GeV/c Yt b P 2 leptons 4 light jets P b b P 3 leptons 2 light jets P b F. Lu, FCPPL-3，Lyon/France

  5. ttH(HWW) Cut flow ( CSC@14TeV ) 2L 3L F. Lu, FCPPL-3，Lyon/France

  6. ttH: Delayed by LHC Accident@2008 • All important effects include: trigger inefficiency, pile up, theo. & instr. Uncertainties were studied. • For the preparation of 2008 real data analysis,also studied BKG data driven estimation & DPDmaker • Unfortunately, 19/Sep./2008 LHC accident had greatly changed LHC Lum. & Ecm Plan, ttH(WW) study is impossible within three years • Tevatron result ruled out MH in 162-164GeV/c2 F. Lu, FCPPL-3，Lyon/France

  7. WH(H->WW*) Estimation of HW coupling (independent on Yukawa coupling) Focus on three leptonic decay final state (two lepton final state also studied but overwhelmed by the W+Jets background) Active Contribution to H production cross section Atlas note (ttH, WH…) 2010-4-8 F. Lu, FCPPL-3，Lyon/France

  8. WH(->WW*) Selection • Sample : CSC MC fulsim sample • Event Selection • At least 3 high pt isolation leptons (leading pt > 35GeV and the rest > 15GeV) • Z Mass Veto (Z lepton candidate with invariant mass 65- 105GeV excluded) • Large Missing Et(>45GeV) • HS Cut(Lepton angular distribution) • B-jet veto (jet activity cut and b veto) • Background Studied: WZ, ttbar, ZZ, ttW, Wbb,W+Jets 2010-4-8 F. Lu, FCPPL-3，Lyon/France

  9. WH(->WW*) Results 2010-4-8 F. Lu, FCPPL-3，Lyon/France

  10. SUSY：decay to 1-2 top pair final state • Extension of ttH to SUSY ( SS-2top, 4top) towards to low lum., top decays provide iso. Leptons or high jet multiplicity which can suppress SM BKG • SUSYis the most promising theory beyond SM • SUSY LSP particle maybe source of dark matter, ~23% universe matter • SUSY mechanics predicts large x-section, may available at lower lum. • SUSY decay has important feature: MET, supress SM BKG SUSY-2top ~g~g →2top + 2c+ 2~10 (LSP) iso. Leptons + at least four Jets + MET SUSY-4top ~g~g → 4top/4W4b + 2~10 (LSP)  1L+ at least 8 jets + MET 0L + at least 10 jets +MET F. Lu, FCPPL-3，Lyon/France

  11. Compressed-SUSY-2top：10TeV • m(~q)=1 TeV • m(~c01)=75 GeV • m(~t1)=110GeV • m(t)=172.5 GeV • Muanza Steve(CPPM): Compressed SUSY SLHA Inclusive SUSY Signal Exclusive SUSY Signal F. Lu, FCPPL-3，Lyon/France

  12. Comparison with Official:Atl-phys-pub-2009-085“Same–sign leptons + 2jets + MET” @10TeV 2010-4-8 F. Lu, FCPPL-3，Lyon/France

  13. Compressed-SUSY-2top: Incl. & Excl. Topology and strategy Excl. Decay Chain: Incl. Topology: Works in progress: • Our X-section is much larger than the official, same trigger: L • Atlas fulsim samples for signal &SM BKG • Same topology & similar selection, but our own optimization • Our SS-2top fulsim analysis shows quite competition relative to the Official result, detail analysis is still in proceeding F. Lu, FCPPL-3，Lyon/France

  14. mSUGRA-SUSY：4top/4W4b final state Sabine Kraml (LSPC): SLHA based on MSSM Sparticle Spectrum ( in GeV ) : ~chi_10: 104 ~chi_20, ~chi_1+ -: 203 ~t1: 350 ~g: 679 ~chi_30,40, ~chi_2+ -: 853-858 ~q, ~l: ~1500 Decay Branching Ratio ( cost = 0.045 ): ~g → ~t1 tbar +cc. 100% , ~t1 → ~chi_10 t : 95.7% ~t1 → ~chi_1+ b: 4.3% , ~chi_1+ → ~chi_10 W+ 100% SUSY-4top production: gg → ~g~g → 4top/4W4b + 2~chi_10( LSP ) NLO (gg  ~g~g) = 1.13 pb at 10 TeV Feasibility is investigated by private fastsim production F. Lu, FCPPL-3，Lyon/France

  15. Fast-Full simulation comparison at 10TeV from ATL-PHYS-PUB-2009-089, triggered by Etjet>70G or MET>30G for early data Fast performance is well for feasibility study F. Lu, FCPPL-3，Lyon/France

  16. ATL-PHYS-PUB-2009-075 14TeV@1fb-1Multi-jets with b-jets Finally ttbar is dominate in BKG F. Lu, FCPPL-3，Lyon/France

  17. Atl-phys-pub-2009-066Jets+MET+0L/1L About JET trigger & lepton trigger: efficiency is high ~99% 2010-4-8 F. Lu, FCPPL-3，Lyon/France

  18. Susy-4top-1L/0L Atlfast Analysis10TeV@200pb-1Work in progress • 1L:  1L(15GeV, iso.)  8jets(20GeV,4jet-80GeV,leading 120GeV) MET>100GeV • triggered by 1L or j70_xE70 • FastAna shows ttbar is well under control • 0L:  10jets(20GeV,4jet-80GeV,leading 120GeV) • MET>100GeV • triggered by j70_xE70 • FastAna shows ttbar & Z()4/5jets • is well under control • Susy-4top has great feature on strong jet activity & MET which can separate it from SM BKG F. Lu, FCPPL-3，Lyon/France

  19. Further Plan ttH CSC analysis established a good base to naturally extend to SUSY area with high x-section Next two years focus on 7TeV real data analysis, especially ttbar(jets) to understand detector performance and BKG behavior Search for SUSY in two samples: susy-2top from 2L sample; susy-4top from 8jets sample; later apply MET>50/100GeV on samples, to carefully compare DATA&MC distribution/yield 2010-4-8 F. Lu, FCPPL-3，Lyon/France 19

  20. Thank you for your attention! Welcome your comments! 2010-4-8 F. Lu, FCPPL-3，Lyon/France

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