1. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) W/Z+  measuerment @ ATLAS On behalf of ATLAS Collaboration Liang HAN University of Science & Technology of China (USTC) ICHEP2012 Melbourne, Australia

2. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20122 s-channel TGC Motivation l ll   W(l )/Z(ll)+  production measurement: FSR ISR: t/u-channel gluon/quark fragmentation  Searching anomalous triple gauge couplings (aTGC):    WW  aTGC :  ,  W magnetic dipole and electric quadrupole moment h  3/4 Z  aTGC : h  3/4 h z 3/4 Z  aTGC : h z 3/4 ZZ  /Z  prohibited by SM + D0, 4.2fb -1 W , PRL107(2011)241803 Prior-LHC results + CDF, 5fb -1 Z , PRL107(2011)051802 + D0, 6.2fb -1 Z , PRD85(2012)052001

3. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20123 Event Selection  ATLAS 7TeV 1fb -1 (35pb -1 ) data: Lepton : + e/  p T >25GeV, detector fiducial |  | coverage; isolated in calorimeter; + Tight electron identification W/Z events : MET>25GeV, MT(l )>40GeV; M(ll)>40GeV Photon : + p T >15GeV, detector fiducial |  | coverage; + Isolated in calorimeter + Tight photon identification + FSR suppression dR(l  )>0.7 + Simulation corrected to Z  ll  data Jet : p T >30GeV, |  | 0.6  Inclusive (>=0jet) vs. Exclusive (==0jet) JHEP 1109,072 ATLAS 35pb -1 result as JHEP 1109,072 arXiv:1205.2531 ATLAS 1.02fb -1 result as arXiv:1205.2531

4. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) FSR ISR 2012/07/03hanl@ICHEP20124  ISR/FSR vs. p T (  cut: High photon p T cut to suppress FSR as Z  : p T (  )  15, 60GeV; W  : p T (  )  15, 60, 100GeV FSR: M(ll  ) ≤ M Z ISR: M(ll  ) > M Z p T (  )  15GeV

5. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20125 W(l )+  control plot Electroweak background derived from simulation Dominant background, W+jet has to be estimated from data

6. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20126 Photon Isolation : W/Z+jet background  2D sideband jet  “  ” background estimation: Photon Identification : based on calorimeter shower-shape

7. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20127 Jet+  background in W   Date-driven jet  “ e/  ” estimation: 1) jet+  : real  ; non-isolated letpon from heavy b/c decay; 2) Control region : MET<20GeV to extract faked “e/  ” isolation shape W(e )  :MET vs. isolation 2-d sideband

8. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20128  Photon E T spectrum: * Signal distribution normalized to the number of extracted data W(l )  inclusiveZ(ll)  inclusive Signal event yield

9. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP20129  Number of jet distribution: p T (  )  60GeV p T (  )  100GeV Inclusive (>=0jet) vs. Exclusive (==0jet) Z(ll)  : p T (  )  60GeV W(l )  : p T (  )  100GeV

10. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201210 Cross section measurement Detector Acceptance Experimental selection efficiency Luminosity 1.024fb -1 ± 3.8%  Unfold detector efficiency: + Correction factor C W  (Z  ) ~ 40 - 60 % + Systematic  C ~ 10 %, dominated by photon identification & jet energy scale

11. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201211 Compared against MCFM  Compare to SM prediction: Estimated from Alpgen/Sherpa + Theoretical uncertainty on acceptance  Theo. ~ 1-3 % + Extend detector fiducial to a uniform lepton |  | coverage  Unfold for detector acceptance : (ISR + FSR + QCD NLO)

12. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201212 Differential cross sections 1) Photon p T  15,60,100GeV ; 2) Inclusive (≥0jet) vs. Exclusive (=0jet) The W  Inclusive are higher than MCFM, especially in high p T (  ) region  high order effects (NNLO and beyond) The Exclusive measurements are consistent with MCFM predictions (SM NLO)

13. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) h  30 =0.05 2012/07/03hanl@ICHEP201213 Anomalous couplings h  3/4 Z  aTGC: h  3/4 h z 3/4 Z  aTGC: h z 3/4 h V 3/4 + aTGC h V 3/4 : ZV  electric dipole / magnetic quadrupole transition moment + non-zero aTGC will result in increasing of W/Z+  cross section, especially in high photon p T region

14. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201214 ZV   Extract ZV  aTGC: + Bayesian probability with nuisance parameters to set limits E T (  )>60GeV + Exclusive E T (  )>60GeV measurement against aTGC hypotheses

15. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201215    WW  aTGC :  ,  WW   Extract WW  aTGC:   =0.4    WW  aTGC :  ,  E T (  )>100GeV Exclusive E T (  )>100GeV measurement against aTGC hypotheses

16. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201216 Summary The differential cross section W(l )  /Z(ll)  measured @ 1fb -1 7TeV ATLAS:  High order effect (NNLO and beyond) is observed in Wγ inclusive (≥0jet) data, especially in high photon p T (  )>60GeV region  Exclusive (=0jet) measurement is consistent with SM NLO Limits on anomalous TGC couplings derived from high photon pT spectrum  WW  aTGC results better than the existing Tevatron limits

17. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201217 Backup slides

18. University of Science & Technology of China (USTC) University of Science & Technology of China (USTC) 2012/07/03hanl@ICHEP201218 Signal event yield  W(l )  :  Z(ll)  : Dominate background as W+jet(“  ”),  +jet (“e”), Z(ll) Dominate background as Z+jet