Atlas Physics China Data Analysis Status

1. Atlas Physics China Data Analysis Status 祝成光 山东大学物理学院 代表ATLAS实验中国组

2. The LHC Machine and Experiments pp at 14 TeV, 1034cm-2s-1 High Energy factor 7 increase w.r.t. present accelerator Tevatron High Luminosity Nevents/(s*T)  factor 100 increase

3. ATLAS Experiment and China Cluster Length ~ 46 m Diameter ~ 25 m Weight ~ 7000Ts Channel ~ 108 Cable ~ 3000km • Muon spectrometer • air-core toroids, • MDT+RPC+TGC+CSC • s/pT ~ 2-7 % • |h|<2.5 (precise phys.) • EM Calorimetry • Pb-LAr • s/E ~ 10%/√E(GeV)1% • |h|<3.2, |h| < 2.5 (fine granularity) • Inner Tracker: • + vertex • + b-tagging • + pT & Q of track • Calorimeter(EM+HD): • + E of e/g • + E of hadron jet • + MET of n(c0) • Muon(outmost tracker): • + pT & Q m • Inner detector (B=2 T) • Si pixels and strips • Transition Radiation Detector (e/ sep) • s/pT ~ 0.05% pT(GeV)0.1%; • |h| < 2.5, B=2 T(central solenoid) • Hadron Calorimeter • Fe/scintillator (central), Cu/W-LAr (fwd) • s/E ~ 50%/√E(GeV)3%, up to ||<3

4. Institution of High Energy Physics (IHEP): • Shandong University (SDU): • Univ. of Science & Technology of China (USTC): • Nanjing University (NJU+SDU): • Higgs search and property study • LCG Teir2 construction • electron energy calibration and ID study • W helicity measurement in top decay • top spin correlation in pair production • single top measurement • WZ production and TGC anomalous coupling • R-parity violation SUSY • single top measurement

5. Higgs production@ LHC q q q q

6. Higgs search@ ATLAS -- SM Higgs (114-190GeV) discovery @ 10 fb-1 -- easy and fast for mH >140 GeV with HWW* channel -- more strength on mH<140 GeV with Htt, Hgg

7. MVA HMatrix: 8 variables_dijet 10 variables_dijet Photon/jet discrimination in Hgg(IHEP) -- Signal : gluon fusion production s(ggHgg)50fbin 95-130GeV mass region -- Background : • irreducible photon pairs continuum sgg1pb/GeV • reducible background s(g+j)103×sgg , s(j+j)106×sgg -- MVA discriminator studies: MVA Fisher: 8 variables_dijet 10 variables_dijet

8. Top Yukawa coupling in ttH(HWW*) (IHEP) -- Precise Yukawa couplings of heaviest fermion, in the intermediate ~160GeV mass gt -- Cross section measurement  coupling constant gt extraction

9. Signal: same-signed 2L + 3L -- Topology and 2L/3L signal channel : • Same-signed 2L/3L • (from Higgs and top) • >=4 high pT jets • Missing ET for >=2n -- irreducible background : tt(1l/2l)+X(W,Z,jets) • lepton in heavy flavor e.g. bc+ln(W*) decay signal same-signed “L” • overwhelming QCD ISR and pileup  signal “jet” Isolation ofLis crucial

10. Calorimeter Isolation: • The total energy deposited in the calorimeter around the lepton in a cone size of 0.2 should smaller than 10GeV • 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 Isolation in Calorimeter and tracker Isolated lepton Uniso. lepton Lepton Calo track Calorimeter Cone size 0.2 Clusters around the lepton Inner detector Tracks around the lepton Electron Muon

11. Theoretical uncertainties -- Uncertainty on Pythia ttH signal : PDF, Q2, ISR/FSR, fragmentation

12. 2L+3L combined prediction @ ATLAS 30fb-1 -- Accuracy on combined σttH×BRHWW -- Accuracy on coupling gt 47.4% (@160GeV) 23.7% (@160GeV)

13. WH(WW*) measurement (IHEP) -- Complementary to heavy Higgs discovery: what if discovered via HZZ4l channel, while WH is absent? -- Measure cross-section to probe Higgs-gauge boson couplings -- Combined 2L+2j and 3L channel

14. Preliminary results

15. Preliminary results -- Normalized to 30 fb-1 • accepted in ATLAS CSC-NOTE • WH coupling measurement in progress

16. Physics of top quark pair production Mass W helicity Charge CP violation Width Anomalous coupling Production cross section Heavy resonance decay Spin correlation Branching ratios CKM :|Vtb| Rare decays

17.  spin=1/2 1/2 1 W polarization and top-pair spin correlation (SDU) -- W helicity in top: σtt@LHC~850pb, Br(tWb)~100% governed by V-A in SM SM prediction(NLO): F0=0.695 FL=0.304 FR=0.001

18. -- top-pair spin correlation: where NLO SM prediction:

19. Single lepton channel analysis -- high BR with moderate background -- in situ W and top mass(transverse) constraints (730pb-1) (220pb-1) * *due to unknown discrepancy between fast and full simulation NLO SM prediction:

20. Di-lepton channel analysis -- rare BR with rare background -- need to solve equations for missing ET of 2n

21. Single top measurement (NJU+SDU) t-channel (~247pb) W+t channel (~66pb) s-channel (~11pb) • The only known way to directly measure CKM matrix element Vtb

22. t-channel cut based analysis results • Processes muon channel electron channel nEvt to L=fb-1 • t-channel 3.83±0.15% 3.10±0.14% 1668 • t-ch (τ)l 1.48±0.23% 0.36±0.11% • s-channel 1.84±0.11% 1.14±0.08% 34 • s-chan (τ)l 0.39±0.12% 0.39±0.12% • W+t channel 0.85±0.07% 0.61±0.02% 136 • W+t chan (τ)l 0.18±0.08% 0.20±0.08% • ttl+jets 0.95±0.03% 0.69±0.02% 4173 • tt(τ)l+j 0.35±0.04% 0.22±0.03% • tte + e 1.83±0.12% • ttμ+μ 3.07±0.16% • ttμ+e 2.10±0.09% • ttμ+τ 3.18±0.11% • tt e +τ 2.41±0.10% • ttτ+τ 0.74±0.08% S/B = 1668/4343 = 38.4%, S/ √ S+B = 21.5

23. s-channel cut based analysis results • Processes muon channel electron channel nEvt to L=fb-1 • s-channel 2.47±0.12% 1.49±0.10% 46 • s-ch (τ)l 0.71±0.16% 0.64±0.15% • t-channel 0.22±0.04% 0.14±0.03% 84 • t-chan (τ)l 0.04±0.04% 0.00±0.00% • W+t channel 0.10±0.03% 0.08±0.03% 11 • W+t chan (τ)l 0.00±0.00% 0.00±0.00% • ttl+jets 0.09±0.01% 0.08±0.01% 646 • tt(τ)l+j 0.04±0.01% 0.02±0.01% • tte + e 0.34±0.05% • ttμ+μ 0.48±0.06% • ttμ+e 0.33±0.04% • ttμ+τ 0.69±0.05% • tt e +τ 0.54±0.05% • ttτ+τ 0.24±0.04% S/B = 46/741 = 6.2%, S/ √ S+B = 1.64

24. s-channel MVA analysis results@1fb-1

25. WZ cross-section and TGC anomalous measurement (USTC) SM NLO : • Phys. Rev. D41, 2782(1990). • Phys. Rev. D47, 940(1993). • Phys. Rev. D60, 114037(1999). • Phys. Rev. D60, 113006(1999) • Unique measurement on WWZ TGC -- non-SM anomalousas with form factor as -- Enhancement on production + excess at W/Z high pT spectrum • WZllln search channel : -- eee, eem, emm and mmm combined, Br~1.5% -- high pT isolated lepton + MET + di-lepton invariant mass around Z -- background Z(ll)+X and ZZ(4l)

26. WZ Observation @ 1fb-1 -- Simple straight cut results

27. R-parity violating sneutrio em resonance (USTC) Parity in SUSY can be partially violated in generic super-potential: -- Tri-linear on-spontaneous B- & L-number violation interactions  stable proton -- Bi-linear couplings  neutrino mass for oscillation -- Constraints from indirect low energy experiments With hypothesis: 1) degenerate M=100GeV 2) single coupling dominance l13k l31k LLE in tenn l312, l321 < 0.07 LQD in tpn l’311 < 0.12 Reference: hep-ph/9906224; Phys. Rept. 420, 1(2005)

28. Expected result @ 1fb-1 -- Phenomenology in collider physics • Y. B. Sun et al., Commun. Theor. Phys. 44, 107 (2005) • L. L.Yang et al., Phys. Rev. D 72, 074026 (2005) • S.M. Wang et al.,Phys. Rev. D 74, 057902 (2006) • H. K.Dreiner et al., Phys. Rev. D 75, 035003 (2007) • Y. Q. Chen et al., J. High Energy Phys. 05 (2007) 068 • S.M. Wang et al., Chinese Phys. Lett. Vol.25, No.1(2008)58 -- Results of measured at Tevatron/D0  expected at ATLAS/LHC PRL 100,241803 10-20 folded improvement on RPV parameter sensitivity would be expected @ATLAS

29. ATLAS run • LHC start tuning on 10/Sep • First Collision expected soon with lower energy. • Understand the detector and data is essential • Follow up with free playing with real data.

30. Summary -- Physics analyses are taking shape, channels cover top, Higgs, EW and SUSY -- Stay tuned for the commissioning run: understanding detector, e.g. e/g efficiency, fake rate, energy scale and resolution, trigger performance etc is the 1st priority -- China LCG Tier2 construction is in good progress; need push university-level distributed Tier3 to be on line in time. -- Young graduates are heartly welcomed to join the team and enjoy yourself in the game for next 10-15 years.