1. (Di-) Boson studies at ATLAS
A concrete collaborating project between CPPM and USTC
Yanwen Liu
USTC and CPPM

2. Outline Electroweak boson production at LHC
From Standard Candle to Physics
ATLAS electron identification
Outlook in place of Conclusion
W,Z WW
For each 100pb-1 , 1M W->eν, 200 pure leptonic WW! (7 TeV PP)
concentrate on ee channel now.

3. WW
Non-zero gauge coupling among bosons

4. Are you so sure?
P-value = 7%
arXiv:
CDF 3.1 fb-1
Leading

5. Higgs, of course! Chinese Scholarship Council
Let’s check it out at ATLAS
Shu LI (thesis student)
CPPM/USTC joint-PhD
+ other PhD students
Supporters: CPPM
F. Hubaut, P. Pralavorio,
E. Monnier
USTC
Y.Liu, Z. Zhao
And
Chinese Scholarship Council
Combined search for gg->H->WW
Bins of each analysis sorted by s/b.
CDF Note 10101, D0 Note 6039

6. CSC results CERN-OPEN-2008-020 Not assessed: W/Z+jets
Multi-jets background
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) .
Need re-optimize for 7 TeV
200 pure leptonic WW events in each 100pb-1

7. Detector for electrons
gluon jets
electrons
from B

8. Good resolution, good s/b
ATLAS test beam
Electron beam
Efficiencies for electrons from Z:
Loose = 88% Tight(isol) = 64%
Medium = 77% Tight(TRT) = 62%

9. Stable operation The “readiness” paper: arXiv:0912.2642
Submitted to EJPC
Stable operation
Constantly monitored : LAr purity, temperature, HV, pedestals and gains

10. Electrons in ‘Standard Candles’
14 TeV MC (performance book)
For 7 TeV, expect 1M electrons per 100pb-1
In progress: preparation for the first W,Z observation with 7 TeV data.

11. “Electrons” in cosmic muons
Electron candidates in cosmic-rays
Checks at electrons variables
Made sure most are truly muons,
saw δ-rays
>= 2 ID tracks

12. Electrons in 900 GeV data

13. Electrons in 900 GeV data

14. ID material from conversions
Brem in TRT
SCT 1

15. One 7 TeV event

16. Another 7 TeV event

17. Outlook in place of Conclusion
ATLAS is an excellent detector
Electron identification promising
Exercised whenever we had a chance
Looking forward to W/Z Standard Candles
Looking forward to exciting physics!