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Yingchuan Li

Weak Mixing Angle and EIC. Yingchuan Li. INT Workshop on Pertubative and Non-Pertubative Aspects of QCD at Collider Energies Sep. 17th 2010. 2. BNL LDRD Electroweak Physics with an Electron-Ion Collider Deshpande, Kumar, Marciano, Vogelsang. STUDY GOALS

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Yingchuan Li

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  1. Weak Mixing Angle and EIC Yingchuan Li INT Workshop on Pertubative and Non-Pertubative Aspects of QCD at Collider Energies Sep. 17th 2010

  2. 2 BNL LDRDElectroweak Physics with an Electron-Ion ColliderDeshpande, Kumar, Marciano, Vogelsang STUDY GOALS • DIS & Nuclear Structure Functions (,Z,W) (Beyond HERA) • ARL,sin2W(Q2), Radiative Corrections, “New Physics” • Lepton Flavor Violation: eg epX

  3. Outline • Why is EW precision physics important? • The past, present, and future (EIC) of • Summary.

  4. 4 Standard Model • SM of particle physics Higgs mechanism • Strong sector: right and complete, hard to solve; • EW sector: still not sure about how EW symmetry breaking happens

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

  6. 6 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! See talk by Del Duca on Wed. • Indirect searchs via precision tests • Z-pole measurements; • Low energy tests of neutral current; What can EIC do on this?

  7. 7 7 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 !

  8. 8 8 8 EW precision tests: three best measured • Fine structure constant: Electron anomalous magnetic moment • Fermi constant: Muon life time • Z boson mass: LEP

  9. 9 9 9 9 The hunt for • Prediction within SM • Z-pole experiment measurements: 3 sigma difference! Correct?

  10. 10 10 10 10 10 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?

  11. 11 11 11 11 11 11 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!

  12. 12 12 12 12 12 Other evidence of • Low energy measurements probe 4-fermion interactions:

  13. 13 13 13 13 13 Other evidence of : neutrino scattering • Neutrino-lepton elastic scattering: • probe • CHARM II: • Neutrino-nucleon DIS: • Paschos-Wolfenstein ratio • probe • NuTeV: Rad. Corr.? Nuclear charge symmetry breaking?

  14. 14 14 14 14 14 14 Other evidence of : Atomic PV • Weak charge: • SM: • 1990: • 1999: • 2008: • 2009: Consistent with Z pole measurement!

  15. 15 15 15 15 15 15 15 Other evidence of : Moller scattering • E158 at SLAC: • Pol. Electron (E=50 GeV) on fixed target: • Meaure to 12%, extract to 0.6% Establish the running of mixing angle (together with APV) to 6 sigma.

  16. 17 17 17 17 17 17 17 17 Future effort to nail • QWEAK exp. At JLAB: ep ep; • Polarized Moller at JLAB: ee ee; • Polarized eD (fixed target) DIS at JLAB (6 & 12 GeV); • Polarized ep & eD collider; Goal: 0.1% accuracy

  17. 18 18 18 18 18 18 18 18 Future effort: QWEAK & Moller • QWEAK at JLAB: • Electron (E=1.1 GeV) on fixed target: • Polarized electron beam: • Meaure to 4%, extract to 0.3% • Moller at JLAB: • Electron on fixed target after 12 GeV upgrade; • Measure to 2.5%, extract to 0.1%

  18. Plot taken from proposal for JLAB Moller scattering

  19. 20 20 20 20 20 20 20 20 20 Future effort: eD DIS • eD (fixed target) DIS: • Advantage: extract • High luminosity: • eD(p) collision DIS: • Larger asymmetry at higher Q-square; • Lower luminosity ( ); • Both electron and deuteron (proton) are polarized;

  20. 21 21 21 21 21 21 21 21 21 21 E-Ion collider: double asymmetry • Polarized e: • Polarized p or D: • Both e & p (D) polarized: • Effective polarization: Larger! Smaller!

  21. 22 22 Summary • Precision tests are very important in revealing the physics behind EW symmetry breaking among other things. • The most precise (0.1%) measurement at Z pole of still has 3 sigma difference. • Another future measurement of with 0.1% precision is demanded. • The EIC may add new twist to it! Thank you !!!

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