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Yingchuan Li

Electroweak physics at EIC. Yingchuan Li. Brookhaven National Lab. Feb. 3rd 2011, BNL. Outline. Introduction: symmetry of SM. Lepton flavor violation at EIC. Weak mixing angle at EIC. Conclusion. 3. Standard Model: symmetry and symmetry breaking. Symmetries:.

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Yingchuan Li

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

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

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

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

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

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

  7. 8 LFV of tau • Various operators: • Magnetic moment operator ; • 4-fermion operators; • Various processes: • tau -> e, gamma; • tau -> 3 e; • e-tau conversion (e p->tau, X);

  8. Theoretical and experimental analysis

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

  10. Weak mixing angle at EIC

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

  12. 15 To ping down the EW symmetry breaking • Direct search at high energy collider • SM Higgs; • SUSY particles; • KK modes; • other exotics; Major motivation for LHC! • Indirect searchs via precision tests • Z-pole measurements; • Low energy tests of neutral current; What can EIC do on this?

  13. 16 16 EW sector with SM Higgs • Three para. (g,g’,v) determine properties of EW gauge bosons • Masses: • EM coupling: • Charged current: • Neutral current: Higgs and top mass enters at loop level !

  14. 17 17 17 EW precision tests: three best measured • Fine structure constant: Electron anomalous magnetic moment • Fermi constant: Muon life time • Z boson mass: LEP

  15. 18 18 18 18 The hunt for • Prediction within SM • Z-pole experiment measurements: 3 sigma difference! Correct?

  16. 19 19 19 19 19 The implications of • World average: Consistent with LEP bound (MH>114 GeV) Suggestive for SUSY (MH<135 GeV) Rule out most technicolor models Satisfied and happy?

  17. 20 20 20 20 20 20 The implications of • SLAC result: + mW=80.398(25) GeV Ruled out by LEP bound (MH>114 GeV) Consistent with LEP bound (MH>114 GeV) Suggestive for SUSY Suggestive for technicolor models • CERN result: + mW=80.398(25) GeV Very different implication! We failed to nail weak mixing angle!

  18. 21 21 21 21 21 21 21 21 21 Past and currently planed experiments: Where does EIC stand?

  19. 22 22 22 22 22 22 22 22 22 Weak mixing at EIC • The good: • Both beam polarized; • High energy: • higher asymmetry, wide coverage of Q. • The bad: • Low luminosity ( ) compared to fixed target experiments ; • The ugly: • Large uncertainty (5%) with the hadron beam polarization; • Large uncertainty with the polarized PDFs;

  20. 23 23 23 23 23 23 23 23 23 Weak mixing at EIC • What are the good asymmetries? • How to control the systematic error? • What is the statistical error with reasonable luminosity?

  21. 24 Single-spin asy. with polarized electron • For ep-DIS: • Simplified for ed-DIS: PDF drops out for isosinglet

  22. 25 Single-spin asy. with polarized hadron • For ep-DIS: • For ed-DIS: Large uncertainty with hadron polarization and polarized PDF

  23. 26 Effective polarization: the trick learned from Moller scattering • Take advantage of effective polarization:

  24. 27 Double-spin asymmetry • Double-spin asymmetry: • Simplified for e-d at kinematic region with y->1:

  25. 28 Good asymmetries • e-p collider: • e-d collider:

  26. 29 29 Monte Carlo simulation: asymmetries • single-spin asymmetry in ep-DIS:

  27. 30 30 Monte Carlo simulation: asymmetries • single-spin asymmetry in ed-DIS:

  28. 31 31 Monte Carlo simulation: Figure of merit • Figure of merit for ep-DIS:

  29. 32 32 Monte Carlo simulation: Figure of merit • Figure of merit for ed-DIS:

  30. 33 33 Monte Carlo simulation: statistical error • Statistical error for ep-DIS:

  31. 34 34 Monte Carlo simulation: statistical error • Statistical error for ed-DIS:

  32. 35 35 35 35 35 35 35 35 35 Past, currently planed, and EIC experiments: • Weak mixing probed at wide range of Q at EIC:

  33. 36 36 Summary • Precision tests are very important probe of BSM • complementary to LHC. • EIC has good chance to • go beyond HERA on bounds on e-tau conversion; • measure over a wide range of Q with statistical error similar to • the Z-pole experiments and other planed low-Q experiments (JLab) ; Thank you !!!

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