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Electroweak Physics at EIC - Summary of Week 7

Explore Electroweak physics at Electron-Ion Collider with focus on Lepton Flavor Violation and Weak Mixing Angle. Learn about the Standard Model, Accidental Symmetries, Search for BSM particles, LFV of Tau, Higgs Mechanisms, Precision Tests, and more.

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Electroweak Physics at EIC - Summary of Week 7

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  1. Electroweak physics at EIC - Summary of week 7 K. Kumar, W. Marciano, Y. Li INT Workshop on Pertubative and Non-Pertubative Aspects of QCD at Collider Energies Nov. 19th 2010

  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(Talks by M. Gonderinger and A. Deshpande)

  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. Weak mixing angle at EIC(Talks by K. Kumar, W. Marciano, and YL)

  10. Scenarios of Higgs mechanism • Fundamental Higgs: hierarchy problem • SUSY; • Extra Dim; • Higgsless models; • Technicolor; • Composite Higgs as a PGB; • Georgi-Kaplan model;

  11. 14 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?

  12. 15 15 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 !

  13. 16 16 16 EW precision tests: three best measured • Fine structure constant: Electron anomalous magnetic moment • Fermi constant: Muon life time • Z boson mass: LEP

  14. 17 17 17 17 The hunt for • Prediction within SM • Z-pole experiment measurements: 3 sigma difference! Correct?

  15. 18 18 18 18 18 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?

  16. 19 19 19 19 19 19 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!

  17. 20 20 20 20 20 20 20 20 20 Past and currently planed experiments: Where does EIC stand?

  18. 21 21 21 21 21 21 21 21 21 Weak mixing at EIC • The good: • Higher asymmetry at high Q: • Both beam polarized; • 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;

  19. 22 22 22 22 22 22 22 22 22 Weak mixing at EIC • What are the good asymmetries? • How to control the systematic error? • What is the required luminosity to reach specific statistical error?

  20. 23 Single-spin asymmetries • For e-p collider: Large x: antiquark contribution negligible, small uncertainty in PDF • Simplified for e-d: PDF drops out for isosinglet Large uncertainty (5%)

  21. 24 Effective polarization • Take advantage of effective polarization:

  22. 25 Double-spin asymmetry • Simplified for e-d at kinematic region with y->1:

  23. 26 Good asymmetries • e-p collider: • e-d collider:

  24. 27 27 Preliminary MC simulation results • single-spin asymmetry in e-p:

  25. 28 28 Preliminary results on reachable precision • e-p collider with polarized electron beam:

  26. 29 29 29 29 29 29 29 29 29 Past, currently planed, and EIC experiments: • Weak mixing probed at wide range of Q at EIC:

  27. 30 30 Summary and outlook • Precision tests are very important probe of BSM • before and after 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) ; • Many things to do • redo the analysis of signal selection efficiency for e-tau at EIC; • a better understanding of systematic error of PVDIS; • think about other topics; Thank you !!!

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