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Yingchuan Li

Weak Mixing Angle at Electron-Ion Collider. Yingchuan Li. Collaboration with William Marciano. DIS 2011, Newport News, VA. Outline. Introduction. Prospects of measuring weak mixing angle at EIC. Conclusion. EW symmetry breaking: still a big puzzle !. So many models:.

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Yingchuan Li

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  1. Weak Mixing Angle at Electron-Ion Collider Yingchuan Li Collaboration with William Marciano DIS 2011, Newport News, VA

  2. Outline • Introduction • Prospects of measuring weak mixing angle at EIC • Conclusion

  3. EW symmetry breaking: still a big puzzle ! • So many models: • Fundamental Higgs: SUSY, Extra Dim., RS… • Higgsless: Technicolor • Composite Higgs: Georgi-Kaplan model, Little Higgs, Gauge-Higgs Unification Hungary for Experimental Data!

  4. 4 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 electroweak • Play important role in the establishment of SM; • Vital role in the establishment of the next model; What can EIC do on this?

  5. 5 5 5 5 The hunt for • Prediction within SM • Z-pole measurements: 3 sigma difference! Correct?

  6. 6 6 6 6 6 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?

  7. 7 7 7 7 7 7 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!

  8. 8 8 8 8 8 8 8 8 8 Past and currently planed experiments: Where does EIC stand?

  9. 9 9 9 9 9 9 9 9 9 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;

  10. 10 10 10 10 10 10 10 10 10 Weak mixing at EIC • What are the good asymmetries? • How to control the systematic error? • What is the statistical error with reasonable luminosity?

  11. 11 Single-spin asy. with polarized electron • For ep-DIS: • Simplified for ed-DIS: PDF drops out for isosinglet

  12. 12 Single-spin asy. with polarized hadron • For ep-DIS: • For ed-DIS: Large uncertainty with hadronpolarization and polarized PDF

  13. 13 Effective polarization: the trick learned from Moller scattering • Take advantage of effective polarization:

  14. 14 Double-spin asymmetry • Double-spin asymmetry: • Simplified for e-d at kinematic region with y->1:

  15. 15 Good asymmetries • e-p collider: • e-d collider:

  16. 17 17 Monte Carlo simulation: asymmetries • single-spin asymmetry in ed-DIS:

  17. 19 19 Monte Carlo simulation: Figure of merit • Figure of merit for ed-DIS:

  18. 21 21 Monte Carlo simulation: statistical error • Statistical error for ed-DIS:

  19. 22 22 22 22 22 22 22 22 22 Past, currently planed, and EIC experiments: • Weak mixing probed at wide range of Q at EIC:

  20. 23 23 Summary • Precision tests are very important probe of BSM • complementary to LHC. • It is highly desirable to have another experiment on weak mixing angle given the 3 sigma difference in two Z-pole experiments. • EIC has good chance to measure over a wide range of Q with statistical error similar to Z-pole experiments. Thank you !!!

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