New Physics Search 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 ) 2010-4-8 F. Lu, FCPPL-3，Lyon/France

F. Lu, FCPPL-3，Lyon/France 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

ttH(HWW)：top Yukawa Coupling measurement Ndata - Nbkg 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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

F. Lu, FCPPL-3，Lyon/France 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 2010-4-8 F. Lu, FCPPL-3，Lyon/France b

ttH(HWW) Cut flow ( CSC@14TeV ) 2010-4-8 F. Lu, FCPPL-3，Lyon/France

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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

F. Lu, FCPPL-3，Lyon/France 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

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

F. Lu, FCPPL-3，Lyon/France WH(->WW*) Results Input(fb) Basic selection Isolation and Z veto Missing Et HS (B) jet veto WH->WW(3L) 5.04 1.18 0.53 0.47 0.36 0.31+/-0.02 WZ 750 165.5 0.74 0.63 0.21 0.10+0.08/-0.06 ttbar 833000 3564.3 6.11 5.10 1.02 0.34+0.70/-0.3 ZZ 72.5 34.5 0.06 0.013 0.008 0.005+/-0.001 ttW 61.1 1.35 0.19 0.07 0.003+0.005/-0.003 Wbb 66700 3.1 _ W(->ev)+Jets 2*10^7 17.6 W(->μv)+Jets 27.6 Total background 0.45+/-0.70 2010-4-8 F. Lu, FCPPL-3，Lyon/France 9

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 SUSY is 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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

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 m(~g) (GeV) sLO (pb) K-factor Ngen Evt Filter Filter e (%) 300 450 1.8 10k Nlep>1 pT>10 GeV |h|<2.7 4.5 400 360 1.3 500 350 0.7 550 0.4 Exclusive SUSY Signal m(~g) (GeV) sLO (pb) K-factor Ngen 300 2.2 1.8 10k 400 0.41 500 0.075 550 0.031 2010-4-8 F. Lu, FCPPL-3，Lyon/France

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

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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

F. Lu, FCPPL-3，Lyon/France 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

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

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

Susy-4top-1L/0L Atlfast Analysis 10TeV@200pb-1 Work in progress  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) 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 2010-4-8 F. Lu, FCPPL-3，Lyon/France

F. Lu, FCPPL-3，Lyon/France 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

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