1. Yingchuan Li Electroweak physics at EIC Brookhaven National Lab Feb. 3rd 2011, BNL

2. Outline 2 Conclusion Lepton flavor violation at EIC Weak mixing angle at EIC Introduction: symmetry of SM

3. 3 Standard Model: symmetry and symmetry breaking 3 Symmetries breaking:  EW gauge symmetry breaking;  Many accidental global symmetries L, B, B-L, LF…;  QCD and EW gauge symmetries; Symmetries:  Broken discrete symmetries C, P, CP;  Dynamical chiral symmetry breaking;

4. 4 LFV: e-tau conversion at EIC (Based on talks by M. Gonderinger and A. Deshpande in INT workshop)

5. 5 Accidental symmetries of SM violated by irrelevant operators – induced by new physics L, B, B-L, LF… respected by relevant operators in SM - specific quantum numbers of SM fields global symmetries (may or may not be gauged); violated in extension of SM - new fields carrying new quantum numbers Search for BSM by search for violation of these symmetries

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7. 7 Flavor & CP problem for BSM What about the new physics scale?  high enough to suppress flavor and CP violations;  low enough to stabilize the EW breaking scale; Hunted for long time but not found (mostly involving first-two generations). Solution: treat the 3 rd generation differently “More minimal SUSY”, Cohen, Kaplan, Nelson 1996; “Warped Extra Dim.”, Randall, Sundrum 1999; Large FV and CPV associated with 3 rd generation

8. 88 LFV of tau Various processes:  Magnetic moment operator ;  e-tau conversion (e p->tau, X);  tau -> 3 e; Various operators:  4-fermion operators;  tau -> e, gamma;

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11. 11 Theoretical and experimental analysis

12. 12 Waiting for Ahbay’s update on experimental aspects. Please stay tuned!

13. 13 Weak mixing angle at EIC

14. 14 Scenarios of Higgs mechanism Higgsless models; Composite Higgs as a PGB; Fundamental Higgs: hierarchy problem  Georgi-Kaplan model;  Extra Dim;  SUSY;  Technicolor; So many models, need experimental evidence!

15. 15 To ping down the EW symmetry breaking Indirect searchs via precision tests Direct search at high energy collider  KK modes;  SM Higgs;  Low energy tests of neutral current;  SUSY particles;  other exotics; What can EIC do on this?  Z-pole measurements; Major motivation for LHC!

16. 16 EW sector with SM Higgs Three para. (g,g’,v) determine properties of EW gauge bosons  Neutral current:  Masses:  EM coupling:  Charged current: Higgs and top mass enters at loop level !

17. 17 EW precision tests: three best measured Z boson mass: Muon life time Fine structure constant: Electron anomalous magnetic moment Fermi constant: LEP

18. 18 The hunt for Correct? Prediction within SM Z-pole experiment measurements: 3 sigma difference!

19. 19 The implications of World average: Rule out most technicolor models Consistent with LEP bound (MH>114 GeV) Suggestive for SUSY (MH<135 GeV) Satisfied and happy?

20. 20 The implications of CERN result: Suggestive for technicolor models Consistent with LEP bound (MH>114 GeV) SLAC result: Suggestive for SUSY Ruled out by LEP bound (MH>114 GeV) + m W =80.398(25) GeV Very different implication! We failed to nail weak mixing angle!

21. 21 Past and currently planed experiments: Where does EIC stand?

22. 22 Weak mixing at EIC The ugly:  Large uncertainty with the polarized PDFs;  High energy: higher asymmetry, wide coverage of Q. The good:  Both beam polarized;  Low luminosity ( ) compared to fixed target experiments ; The bad:  Large uncertainty (5%) with the hadron beam polarization;

23. 23 Weak mixing at EIC How to control the systematic error? What is the statistical error with reasonable luminosity? What are the good asymmetries?

24. 24 Single-spin asy. with polarized electron Simplified for ed-DIS: PDF drops out for isosinglet For ep-DIS:

25. 25 Single-spin asy. with polarized hadron For ed-DIS: For ep-DIS: Large uncertainty with hadron polarization and polarized PDF

26. 26 Effective polarization: the trick learned from Moller scattering Take advantage of effective polarization:

27. 27 Double-spin asymmetry Simplified for e-d at kinematic region with y->1: Double-spin asymmetry:

28. 28 Good asymmetries e-d collider: e-p collider:

29. 29 Monte Carlo simulation: asymmetries single-spin asymmetry in ep-DIS:

30. 30 Monte Carlo simulation: asymmetries single-spin asymmetry in ed-DIS:

31. 31 Monte Carlo simulation: Figure of merit Figure of merit for ep-DIS:

32. 32 Monte Carlo simulation: Figure of merit Figure of merit for ed-DIS:

33. 33 Monte Carlo simulation: statistical error Statistical error for ep-DIS:

34. 34 Monte Carlo simulation: statistical error Statistical error for ed-DIS:

35. 35 Past, currently planed, and EIC experiments: Weak mixing probed at wide range of Q at EIC:

36. 36 Summary Precision tests are very important probe of BSM complementary to LHC. Thank you !!!  measure over a wide range of Q with statistical error similar to the Z-pole experiments and other planed low-Q experiments (JLab) ; EIC has good chance to  go beyond HERA on bounds on e-tau conversion;