ATLAS PHYSICS STUDY in CHINA 南昌高能物理大会 – 冯 存 峰 ( 山东大学 ) On behalf of Atlas Chinese Cluster (IHEP, Nanjing U., Shandong U., USTC)

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 22 Outline Introduction Standard model (electroweak) tests Top physics Higgs search and property SUSY Detector commissioning Summary

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 3 Introduction The LHC status

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 4 Physics is now at our door !

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 5 WZ studies WZ production can involve TGC and sensitive to new physics First observed by CDF - PRL 98, (2007) Little is known so far… First observation of WZ at CDF cross section measurement with early ATLAS data a precision electroweak test assess systematic effects for multi- lepton analyses – crucial for H->ZZ … cross section measurement with early ATLAS data a precision electroweak test assess systematic effects for multi- lepton analyses – crucial for H->ZZ … As early as when MET and multivariate techniques are not fully commissioned Apply basic cut based lepton identifications only. As early as when MET and multivariate techniques are not fully commissioned Apply basic cut based lepton identifications only.

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 6 CSC results of WZ analysis at ATLAS

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 7 Prospect for 1/fb: event yield, cross section precision eeeeemmmemmm WZ ZZ ZPhoton ttbar WW Total background Δσ/σ (stat)38.7%21.1%22.0%15.2% Δσ/σ (total)56.4%22.4%24.6%16.8% 4-channel combination: uncertainty correlations accounted for. a 10% measurement! large room for optimization based on v14 MC samples

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 8 Ttbar cross section Ttbar Total:160pb Semi-lepton: 48pb Di-lepton: 8pb

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 9 Ttbar (200pb -1 ) Event selection Exactly one lepton (electron or muon) with pT> 20 GeV. Missing ET > 20 GeV. At least four jets with pT> 20 GeV. at least three jets have pT> 40 GeV. No b-jet tag used ATL-PHYS-PUB

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 10 Ttbar semi-leptonic cross section Wm cut Cut and count Top mass fit Electron Mu

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 11 uncertainties systematic

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 12  tt spin correlation parameters with final objects Angle between spin analysers Angle between t(t) and spin analysers  W polarization analysis with final objects angle between lepton in W rest frame and W direction in top rest frame  1,  2  1,  2  spin analyzer qualities  (l + ) =1,  (b)=-0.41 For V-A:  (l + ) =1,  (b)=-0.41…. SM predictions for these parameters ttbar spin correlation and W polarization

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 13 * due to unknown discrepancy between fast and full simulation (730pb -1 ) (220pb -1 ) * Single lepton channel analysis -- high BR with moderate background -- in situ W and top mass(transverse) constraints SM predictions W polarization: Preparing for summer CONF note

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 14 Single Top Quark Production at LHC Single top production  Weak production mechanism: Wtb vertex  Signature: 1 central high-p t b-jet, W leptonic decay, 1-2 extra jets 14 σ NLO ~3 pb (7TeV) ~11 pb (14TeV) σ NLO ~ 15 pb (7TeV) ~ 66 pb (14TeV) s-channel Wt t-channel σ NLO ~ 60 pb (7TeV) ~246 pb (14TeV)

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 15 Single top t-channel Analysis (14TeV) 15 Event Selection harder b-jet cut: p T >50 GeV forward light jet cut |η|>2.5 (cut based analysis only) 1 BDT discriminant vs top pairs Sourceδσ/σ cut-basedδσ/σ BDT Stat. error5.0%5.7% MC stat.6.5%7.9% Luminosity18.3%8.8% B-tag efficiency18.1%6.6% Jet energy scale21.6%9.9% Lepton ID, trigger2.3%1.8% Theory (xs, PDF, ISR/FSR…) 28.1%13.5% Total 1(10) fb -1 45% (22%)22% (10%) S~4412 S/B=0.12 S~540 S/B=1.3 BDT Cut 1fb -1 CSC note

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 16 Top Yukawa coupling in ttH(H  WW*) gtgt  轻子和夸克通过与 Higgs 粒子的 Yukawa 耦合获得质量。  通过 ttH 过程研究 top 夸克的 Yukawa 耦合，可能是 LHC 唯一可测量的 Yukawa 耦合常数 -- Cross section measurement  coupling constant g t extraction

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 17 Signal & Background b b 4 light jets 2 leptons P P b b 2 light jets 3 leptons P P Signal 1 ： ttH  2b4j2l2V l  6jets + 2 same charge lep. + MissEt Possible BGs: tt(1l), tt(2l), ttZ, ttW, tttt, ttWW, ttbb... Signal 2 ： ttH  2b2j3l3V l  4jets + 3leptons + MissEt Possible BGs: tt(2l),ttZ,ttW,tttt,ttWW,ttbb Lepton Isolation is crucial Balance between statistic and s/b, only study: 2 same change lepton channel, & 3 lepton channel

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 18 Isolation in Calorimeter and tracker Clusters around the lepton Lepton Cone size 0.2 Tracks around the lepton Inner detector Calorimeter Tracker Isolation: The maximum pt of extra tracks in ID around the lepton in a cone size of 0.2 should smaller than 2 GeV Calorimeter Isolation: The total energy deposited in the calorimeter around the lepton in a cone size of 0.2 should smaller than 10GeV ElectronMuon Calo track Isolated lepton Uniso. lepton

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 19 Combined systematic uncertainties Take 10%

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 20 Expectec direct measurement results Result uncertainties dominated by Background systematic uncertainty, to estimate and correct it by a real data driven method is essential ! precision(160GeV): 2L : 69% 3L : 66% Combined: 47%

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 21 If 20% systematicsWH2LWH3LCombined Significance %64%47% Apr 2, 2008Lian-You SHAN, 30 inverse fb, accepted in ATLAS CSC-NOTE WH coupling measurement needs more work to improve WH coupling in: WH(H->WW*)

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 22

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 23 γ Trigger Efficiency plot with 10pb -1 This plot is using γ+jet events, which corresponding to 10 pb-1. It is possible to implement these methods with low statistic. Work in progress g20_loose trigger near 100% for pT>25GeV

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 24 寻找 R 宇称破坏的 e  超对称粒子

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 25 Expected （ preparing for summer CONF note ） M = 100 GeV M = 125 GeV M = 150 GeV M = ATLAS: D0: ATLAS: D0: 在 1fb -1 相同亮度下， ATLAS 对 R 宇称 破缺参数灵敏度预期，好于现有 D0 实 验测量 PRL 100, (2008) 近一个 量级

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 26

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 27 From D.

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 28 b-jet tag B Tagging Efficiency Light Jet Mistag Rate B Tagging Efficiency Light Jet Mistag Rate B Tagging Efficiency W+jets events QCD events W+jets events QCD events B Jet Identification Tag. eff. & Mistag on going J. J.

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 29 SV0 b tag studies Primary Vertex Secondary Vertex Tracks Jet Direction Decay Length Significance: Performance studies Correlation between Btag estimator studies Miss-tag rate estimate from data Discrimination Power: Heavy Flavor Jet: tend to be positive Light Flavor Jet: presence of a secondary vertex (resolution effect of light jet) In parallel, tracking DPD maker validation (on data) Bai

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 30 Summary LHC and ATLAS is almost ready for physics now, need more performance study Many works done  Hardware, Detector commissioning, Computing facility  MC study  Few conf notes are preparing Many subjects are in exploration  Many challenges ahead  Your suggestion are welcome. Looking forward to exciting physics!

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 31 ATLAS 中国组欢迎你的建议和帮助！ 谢谢！

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 32 backup

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 33 (Di-)Boson Electroweak boson production at LHC  From Standard Candle to Physics ATLAS electron identification W,Z WW For each 100pb -1, 1M W->eν, 200 pure leptonic WW! (7 TeV PP) concentrate on ee channel now. From Y.

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 34 WW Two isolated leptons, pT>20 GeV, |η|<2.5 Veto events with a jet of pT>20 GeV, |η|<3. MET > 50 GeV Veto on events with a Z peak. Angular cuts among leptons and MET (different for WW cross section measurement and anomalous coupling sensitivity). CERN-OPEN pure leptonic WW events in each 100pb -1 Need re-optimize for 7 TeV Higgs, of course! gg->H->WW

Cunfeng Feng Single top meetingFCPPL workshop, Wuhan 35 Z+γ production on going: (σ (zγ  From M. SM forbidden