China ATLAS Status report

HAN LiangUniv. of Sci. & Tech. of China

On behalf of China ATLAS collaborate

2

The LHC Machine and Experiments

pp at 14 TeV, 1034cm-2s-1

s

High Energy factor 7 increase w.r.t. present accelerator Tevatron High Luminosity Nevents/(T) factor 100 increase

Inner detector (B=2 T)• Si pixels and strips• Transition Radiation Detector (e/ sep)• /pT ~ 0.05% pT(GeV)0.1%; • || < 2.5, B=2 T(central solenoid)

Hadron Calorimeter• Fe/scintillator (central), Cu/W-LAr (fwd)• /E ~ 50%/√E(GeV)3%, up to ||<3

Muon spectrometer• air-core toroids, MDT+RPC+TGC+CSC•/pT ~ 2-7 %• ||<2.5 (precise phys.)

EM Calorimetry • Pb-LAr• /E ~ 10%/√E(GeV)1%• ||<3.2, || < 2.5 (fine granularity)

Length ~ 46 m Diameter ~ 25 m Weight ~ 7000TsChannel ~ 108 Cable ~ 3000km

ATLAS Experiment and China Cluster

• Inner Tracker: + vertex + b-tagging + pT & Q of track

• Calorimeter(EM+HD): + E of e/ + E of hadron jet + MET of

• Muon(outmost tracker): + pT & Q

Institution of High Energy Physics (IHEP):• Higgs search and property study• LCG Teir2 construction• electron energy calibration and ID study

Shandong University (SDU):• W helicity measurement in top decay• top spin correlation in pair production • single top measurement

Univ. of Science & Technology of China (USTC):• WZ production and TGC anomalous coupling• R-parity violation SUSY

Nanjing University (NJU):• single top measurement

Higgs production@ LHC

q

q

q

q

-- SM Higgs (114-190GeV) discovery @ 10 fb-1

-- easy and fast for mH >140 GeV with HWW* channel

-- more strength on mH<140 GeV with HH

Higgs search@ ATLAS

Photon/jet discrimination in H(IHEP)

-- Signal : gluon fusion production (ggH)50fb in 95-130GeV mass region

-- Background : • irreducible photon pairs continuum 1pb/GeV • reducible background (+j)103×(j+j)106×

MVA Fisher:

8 variables_dijet

10 variables_dijetMVA HMatrix:

8 variables_dijet

10 variables_dijet

-- MVA discriminator studies:

Top Yukawa coupling in ttH(HWW*) (IHEP)

gt

-- Precise Yukawa couplings of heaviest fermion, in the intermediate ~160GeV mass

-- Cross section measurement coupling constant gt extraction

Signal: same-signed 2L + 3L -- Topology and 2L/3L signal channel :

-- irreducible background : tt(1l/2l)+X(W,Z,jets)

• Same-signed 2L/3L (from Higgs and top)

• >=4 high pT jets

• Missing ET for >=2

• lepton in heavy flavor e.g. bc+l(W*) decay signal same-signed “L”• overwhelming QCD ISR and pileup signal “jet”

Isolation of L is crucial

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

Electron MuonC

alotrack

Isolated lepton

Uniso. lepton

Theoretical uncertainties

-- Uncertainty on Pythia ttH signal : PDF, Q2, ISR/FSR, fragmentation

-- Accuracy on combined σttH×BRHWW -- Accuracy on coupling gt

47.4% (@160GeV)

23.7% (@160GeV)

2L+3L combined prediction @ ATLAS 30fb-1

WH(WW*) measurement (IHEP)

-- Measure cross-section to probe Higgs-gauge boson couplings

-- Combined 2L+2j and 3L channel

-- Complementary to heavy Higgs discovery: what if discovered via HZZ4l channel, while WH is absent?

Preliminary results

If 20% systematics WH2L WH3L Combined

Significance 1.6 1.9 2.4

67% 64% 47%

Preliminary results

-- Normalized to 30 fb-1

• accepted in ATLAS CSC-NOTE• WH coupling measurement in progress

Production cross section

Heavy resonance decay

W helicity

Anomalous coupling

CP violationCharge

Width

Mass

Spin correlation

Rare decays

Branching ratiosCKM :|Vtb|

Physics of top quark pair production

W polarization and top-pair spin correlation (SDU)

spin=1/2 1 1/2

-- W helicity in top: σtt@LHC~850pb, Br(tWb)~100% governed by V-A in SM

222

0 2

cosΨ1

2

cosΨ1

2

sinΨ

2

3

dcosΨ

dN1 +F+F+F=

N RL

SM prediction(NLO):

F0=0.695 FL=0.304 FR=0.001

-- top-pair spin correlation:

)coscos1(4

1

)(cos)(cos

12121

21

2

Add

Nd

N

1 2

1 1(1 cos )

cos 2 D

dNA

N d

L L R R L R R L

L L R R L R R L

σ(t t )+σ(t t )-σ(t t )-σ(t t )

σ(t t )+σ(t t )+σ(t t )+(t t )0.422A

where NLO SM prediction:

0.290DA

*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

NLO SM prediction:

Di-lepton channel analysis

-- rare BR with rare background -- need to solve equations for missing ET of

(syst)±(stat)±=F

(syst)±(stat)±=F

(syst)±(stat)±=F

R

L

0.0390.0270.005

0.0790.0260.297

0.0760.0440.7090

Single top measurement (NJU)

• The only known way to directly measure CKM matrix element Vtb

t-channel(~247pb)

W+t channel(~66pb)

s-channel(~11pb)

• Try to distinguish s-channel from t-channel production mode to test SM

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%

• ttl+jets 0.95±0.03% 0.69±0.02% 4173• tt(τ)l+j 0.35±0.04% 0.22±0.03% • tte + e 1.83±0.12% • ttμ+μ 3.07±0.16% • ttμ+ e 2.10±0.09% • ttμ+τ 3.18±0.11% • tt e +τ 2.41±0.10% • ttτ+τ 0.74±0.08%

S/B = 1668/4343 = 38.4%, S/ √ S+B = 21.5

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%

• ttl+jets 0.09±0.01% 0.08±0.01% 646• tt(τ)l+j 0.04±0.01% 0.02±0.01% • tte + e 0.34±0.05% • ttμ+μ 0.48±0.06% • ttμ+ e 0.33±0.04% • ttμ+τ 0.69±0.05% • tt e +τ 0.54±0.05% • ttτ+τ 0.24±0.04%

S/B = 46/741 = 6.2%, S/ √ S+B = 1.64

channel\classifiers

BDTBDT

DMLP

LikelihoodD

TMlpANN

RuleFitsch-cut

s-channel 50.3 46.0 36.0 40.1 40.0 35.0 46

t-channel 39.7 15.9 19.0 36.5 17.0 31.7 84

W+t channel 6.1 6.6 6.6 5.0 3.3 8.2 11

tt-->l+jets 88.9 64.7 70.2 114.7 45.2 104.5 223

tt-->di-lep 48.4 29.6 35.1 67.1 23.4 48.4 150

tt-->l+tau104.

5 75.7 74.1 141.2 60.1 97.5 273

all BKG287.

6 192.

5 205.

0 364.5 149.0 290.3 741

S/B17.5

%23.9

%17.6

%11.0% 26.8% 12.1% 6.2%

S/sqrt(S+B) 2.74 2.98 2.32 1.99 2.91 1.94 1.64

s-channel MVA analysis results@1fb-1

SM NLO : ~ pb,2 ~ pb9.4 18.4W Z W Z

Unique measurement on WWZ TGC

-- non-SM anomalous as with form factor as Z Z1 1 Z Zg g 1, κ κ 1, λZ

-- Enhancement on production + excess at W/Z high pT spectrum

WZlll search channel :

-- high pT isolated lepton + MET + di-lepton invariant mass around Z-- background Z(ll)+X and ZZ(4l)

-- eee, ee, e and combined, Br~1.5%

02 2

ˆ( )ˆ(1 / )

aa s

s

WZ cross-section and TGC measurement (USTC)

• Phys. Rev. D41, 2782(1990).• Phys. Rev. D47, 940(1993).• Phys. Rev. D60, 114037(1999).• Phys. Rev. D60, 113006(1999)

WZ Observation @ 1fb-1

-- Simple straight cut results

' ''2

1 1ˆˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ2 2

ijk k kijijka b a b a b

R ab i j k ab i j k i j ab i iW L L E L Q D U D D L H

R-parity violating sneutrio em resonance (USTC)

-- Tri-linear on-spontaneous B- & L-number violation interactions stable proton

-- Bi-linear couplings neutrino mass for oscillation -- Constraints from indirect low energy experiments

13k

31k

LLE in e312, 321 < 0.07 LQD in ’311 < 0.12

With hypothesis: 1) degenerate M=100GeV 2) single coupling dominance

Reference: hep-ph/9906224; Phys. Rept. 420, 1(2005)

Parity in SUSY can be partially violated in generic super-potential: 2 31

S L BR

-- Phenomenology in collider physics

Expected result @ 1fb-1

-- 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

• 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

Prepare for Commissioning Run

-- Full Dress Rehearsal

Complete test on DAQ test by physics processes after Event Filters, e.g. Trigger ”e25i”

single e (pT>20GeV)

di-e(pT>20GeV,d)

• CTB2004 is the first beam test integrating all sub detector

• All sub detectors are the final prototype of ATLAS detector

• First dedicated runs for energy <10GeV particles

-- Combined Test Beam 2004: to calibrate electron energy linearity (IHEP)

Summary

-- Physics analyses are beginning to take shape, channels cover top, Higgs, EW and SUSY

-- Stay tuned for the commissioning run: understanding detector, e.g. e/ 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.

Backup slides

ttH(HWW) Cut flow

2L

3L

Pileup event effects

Significance=S/sqrt(B): 3.0 2.4 ( -20% ! )

Summary of systematic

Physics and Performance Goal of 2008 run (L=100pb-1)

Fast G4 Simulationimportant for reducing systematic errors

Fast G4 simulation and full simulationJet pT spectra (in GeV) in release 13.0.30.3 ttbar events

Pier-Olivier DeViveiros

Full SimFast G4 Sim

Full SimFast G4 Sim

How to quickly access data?

• Tier-2 in China is badly needed

• Before the tier-2 is ready (in two years?), the best way seems to send people to France under the FCPPL frame.

总 结• LHC 物理研究意义重大；中国应加强对 LHC 物理研究的投入

（人力和经费）。

• 中国组出色完成了 LHC 各个实验探测器建造任务，为参加物理分析取得了“参赛权”。

• 尽管物理分析起步较晚， ATLAS/CMS/LHCb 中国组仍在Higgs 、 SUSY 、味物理（ top 和 b 物理）、电弱理论和 QCD检验等各个方面取得了良好进展，其中 ATLAS 中国组有四个分析被合作组接受包括在即将正式发表的 CSC Note 里（尤其是 ttH 分析由高能所成员任召集人）， CMS 中国组有一个分析列入已正式发表的 Physics TDR 。

• 我们迫切需要 Tier-2 尽快在国内建成。