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Electroweak Physics At The EIC (Electron-Ion Collider)

Electroweak Physics At The EIC (Electron-Ion Collider) William J. Marciano (May 17, 2010) 1. WEAK NC PARITY VIOLATION i) APV vs Pol Electron Scattering

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Electroweak Physics At The EIC (Electron-Ion Collider)

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  1. Electroweak Physics At The EIC (Electron-Ion Collider) William J. Marciano (May 17, 2010) 1. WEAK NC PARITY VIOLATION i) APV vs Pol Electron Scattering ii) QWEAK, Moller, DIS (eD&ep) 2. Preliminary Collider Requirements For Competitive ARL Program ~100fb-1 (K. Kumar et al.) 2009 Talk *3. Utility of Both Beams Polarized

  2. EIC Physics Case Must be primarily a Nuclear/QCD Facility Structure functions (polarized), small x gluons… Properties of quarks in nuclei (EMC effects)… Sum rules (Bj), (Q2)QCD… HERA(ep): L~1031cm-2s-11033,34,35cm-2s-1 polarized e,p,D,3He; Heavy Ions What about Electroweak Physics? Second Detector? Complementary Program!

  3. BNL/LDRD Proposal 2009Electroweak Physics with an Electron-Ion Collider(Deshpande, Kumar, Marciano, Vogelsang) • DIS & Nuclear Structure Functions (,Z,W) (Beyond HERA) Bjorken Sum Rule, Polarized EMC… • ARL,sin2W(Q2), Radiative Corrections, “New Physics” • Lepton Flavor Violation: eg epX (1000fb-1!) Various Issues That Need Thorough Study What are the Machine and Detector Requirements? Inclusion of Electroweak Radiative Corrections (Important?) High Precision & Polarization(0.5%?, 0.25%?) Proton, D, 3HE Polarization (Spin Content-Other?)

  4. 1) PV Weak Neutral Currents(Past, Present and Future) • Ancient History: By 1975 the SU(2)LxU(1)Y Weinberg-Salam Model was nearly established. Predicted Weak Neutral Currents seen in neutrino scattering at CERN! But did the NC have the right coupling? g2/cosWZf(T3f-2Qfsin2W -T3f5)f A New Form of Parity Violation! Non Maximal but Distinctive -Z Interference  Parity Violation Everywhere!

  5. Atomic Parity Violation (APV) • QW(Z,N) =Z(1-4sin2W)-N Weak Charge W=Weak Mixing Angle QW(p)=1-4sin2W=0.07 QW(209Bi83) = -43 -332sin2W =-127 Bi Much Larger but Complicated Atomic Physics Originally APV not seen in Bi  SM Ruled Out? (Later seen in Tl, Bi, Cs…) 1978 SLAC Polarized eD Asymmetry (Prescott, Hughes…)e+De+X -Z Interference ARL= R-L/R+L2x10-4Q2GeV-2(1-2.5sin2W)~10-4Expected Exp. Gave ARLexp=1.5x10-4sin2W=0.21(2)

  6. Confirmed SU(2)LxU(1)Y SM! ±10% Determination of sin2W Precision! Seemed to agree with GUTS (SU(5), SO(10)…) sin2W=3/8 at unification =mX2x1014GeV sin2W(mZ)MS=3/8[1-109/18ln(mX/mZ)+…] 0.21! (Great Desert?) But later, minimal SU(5) ruled out by proton decay exps (pe+)>1033yr mX>3x1015GeV SUSY GUTUnification(msusy~1TeV)mX1016GeV p1035-1036yr sin2W(mZ)MS=0.233 (Good Current Agreement!)

  7. 1980s - Age of EW Precision sin2W needed better than 1% determination Renormalization Prescription Required EW Radiative Corrections Computed Finite and Calculable: DIS N, ve, APV (A. Sirlin &WJM) mZ, mW, Z, ALR,AFB Define Renormalized Weak Mixing Angle:sin2WR sin20W=1-(m0W/m0Z)2=(e0/g0)2 Natural Bare Relation sin2W1-(mW/mZ)2 On Shell Definition, Popular in1980s Induces large (mt/mW)2 corrections Now Largely Abandoned sin2W()MSe2()MS/g2()MS Good for GUT running No Large RC Induced Theoretically Nice/ But Unphysical

  8. sin2Wlep =Z coupling at the Z pole very popular at LEP = sin2W(mZ)MS+0.00028 (best feature) sin2W(Q2) = Physical Running Angle Continuous Incorporates Z mixing loops: quarks, leptons, W Precision measurements at the Z Pole (e+e-Zff) Best Determinations sin2W(mZ)MS = 0.23070(26) ALR (SLAC) sin2W(mZ)MS = 0.23193(29) AFB(bb) (CERN) (3.2 sigma difference!)

  9. Leptonic vs Hadronic Z Pole Averages sin2W(mZ)MS = 0.23085(21) Leptonic sin2W(mZ)MS = 0.23194(27) Hadronic (Also differ by > 3sigma) World Average: sin2W(mZ)MS=0.23125(16) IS IT CORRECT? (Major Implications)

  10. -1=137.035999, G=1.16637x10-5Gev-2,mZ=91.1875GeV + mW=80.398(25)GeVsin2W(mZ) = 0.23104(15) Implications: 114GeV<mHiggs<150GeV. New Physics Constraints From: mW, sin2W, ,& G S=ND/6 (ND=# of heavy new doublets, eg 4th generationND=4) mW*= Kaluza-Klein Mass (Extra Dimensions) GG(1+0.0085S+O(1)(mW/mW*)2+…) sin2W(mZ)MS S ND&mW* Average 0.23125(16) +0.11(11) 2(2), mW*3TeV ALR 0.23070(26) -0.18(15) (SUSY) AFB(bb) 0.23193(29) +0.46(17) 9(3)! Heavy Higgs, mW*~1-2TeV Very Different Interpretations. We failed to nail sin2W(mZ)MS!

  11. What about low energy measurements? • DIS  Scattering: R(NX)/(NX) loops  mt heavy, sin2W(mZ)MS=0.233SUSY GUTS NuTeV sin2W(mZ)MS=0.236(2) High? Rad. Corr.?Nuclear-Charge Symmetry Violation? Atomic Parity Violation Strikes Back 1990 QW(Cs)exp=-71.04(1.38)(0.88) C. Wieman et al. Electroweak RCQW(Cs)SM=PV(-23-220PV(0)sin2W(mZ)MS) =-73.19(3) 1999 QW(Cs)exp=-72.06(28)(34) Better Atomic Th. 2008 QW(Cs)exp=-72.69(28)(39)sin2W(mZ)MS=0.2290(22) 2009 QW(Cs)exp=-73.16(28)(20)sin2W(mZ)MS=0.2312(16)! 0.5%  Major Constraint On “New Physics” QW(Cs)=QW(Cs)SM(1+0.011S-0.9(mZ/mZ)2+…) eg S=0.00.4 mZ>1.2TeV, leptoquarks, …

  12. Radiative Corrections to APV QW(Z,N)= PV(-N+Z(1-4PVsin2W(mZ)MS) PV=1-/2(1/s2+4(1-4s2)(ln(mZ/M)2+3/2)+….)0.99 PV(0)=1-/2s2((9-8s2)/8s2+(9/4-4s2)(1-4s2)(ln(mZ/M)2+3/2) -2/3(T3fQf-2s2Qf2)ln(mZ/mf)2+…)1.003 s2sin2W(mZ)MS=0.23125, M=Hadronic Mass Scale Radiative Corrections to APV small and insensitive to hadronic unc. Same Corrections Apply to elastic eN scattering as Q20, Ee<<mN

  13. E158 at SLAC Pol eeee Moller)Ee50GeV on fixed target, Q2=0.02GeV2 ALR(ee)=-131(14)(10)x10-9  (1-4sin2W) EW Radiative Corretions -50%! (Czarnecki &WJM) Measured to 12% sin2W to 0.6% sin2W(mZ)MS=0.2329(13) slightly high Best Low Q2 Determination of sin2W ALR(ee)exp=ALR(ee)SM(1+0.13T-0.20S+7(mZ/mZ)2…) Constrains “New Physics” eq mZ>0.6TeV, H--,S, Anapole Moment, … Together APV(Cs) & E158 sin2W(Q2) running sin2W(mZ)MS=0.232(1)

  14. Goals of Future Experiments • High Precision: sin2W0.00025 or better • Low Q2 Sensitivity to “New Physics” mZ’ >1TeV, S<0.1-0.2, SUSY Loops, Extra Dim., 4th Generation….

  15. Other ALR Experiments Strange Quark Content Program: Bates, JLAB, MAMI Proton strange charge radius and magnetic moment consistent with 0. Axial Vector effects and RC cloud strangeness. PREX Experiment: Neuton distribution Preparing the way for future experiments, pushing technology and instrumentation, polarization

  16. Future Efforts QWEAK exp at JLAB Will measure forward ALR(epep)  (1-4sin2W)=QW(p) E=1.1GeV, Q20.03GeV2, Pol=0.801%ARL(ep)3x10-7 small ARL requires long running Goal sin2W(mZ)MS=0.0008 via 4% measurement of ALR Will be best low energy measurement of sin2W ALR(ep)exp=ALR(ep)SM(1+4(mZ/mZ)2+…) eg mz~0.9TeV Sensitivity (Not as good as APV) • The Gorchtein - Horowitz Nightmare (PRL) Z box diagrams: O(2Ee/mp) 6% of QW(p)! Recently Confirmed (Improved): Sibirtev et al.; Gorchtein et al. Proposed Qweak Theory Uncertainty < 2% JLAB Flagship Experiment

  17. Longer Future Efforts: Polarized Moller at JLAB After 12GeV Upgrade ALR(eeee) to 2.5% sin2W(mZ)MS=0.00025! Comparable to Z pole studies! ALR(ee)exp=ALR(ee)SM(1+7(mZ/mZ)2+…) Explores mZ1.5TeV Better than APV, S0.1 etc. Future JLAB Flagship Experiment!

  18. HPV=G/2[(C1uuu+C1ddd)e5e+HPV=G/2[(C1uuu+C1ddd)e5e+ (C2uu5u+C2dd5d)ee+…] QW(p)=2(2C1u+C1d) QW(Cs)=2(188C1u+211C1d) What about the C2q?

  19. What About C2u and C2d? • Renormalized at low Q2 by Strong Interactions Measure in Deep-Inelastic Scattering (DIS), eD & ep ARL(eDeX)2x10-4GeV-2Q2[(C1u-C1d/2)+f(y)(C2u-C2d/2)] f(y)=[1-(1-y)2]/[1+(1-y)2] Standard Model: C1u= (1-8sin2W/3)/2  0.20 C1d=-(1-4sin2W/3)/2 -0.32 C2u= (1-4sin2W)/2 0.04 C2d =-(1-4sin2W)/2-0.04 C2q sensitive to RC & “New Physics” eg Z (SO(10)) Measure ARL to 1/2%? Measure C2q to 1-2%? Theory (loops)?

  20. JLAB 6 GeV DIS eDeX Proceeding JLAB 12 GeV DIS eD Future Goals: Measure C2qs, “New Physics”, Charge Sym. Violation … Effective Luminosity (Fixed Target) 1038cm-2sec-1! What can ep and eD at e-Ion contribute? Asymmetry F.O,M,A2N, AQ2, N1/Q2 (acceptance?) High Q2 Better (but Collider Luminosity?) K. Kumar Talk 100fb-1 (L1034cm-2s-1) Needed Program can be started with lower luminosity Do DIS ep, eD, eN at factor of 10 lower (Polarized p & Nuclei)Bjorken Sum Rule, Pol Structure Functions, Spin Distribution…

  21. Single and Double Polarization Asymmetries Polarized e: AeRL=(RR+RL-LL-LR)/(RR+RL+LL+LR)Pe Polarized p: ApRL=(RR+LR-RL-LL)/(RR+LR+RL+LL)Pp Polarized e&p AepRRLL= (RR-LL)/(RR+LL)Peff Peff=(Pe-Pp)/(1-PePp) opposite signs like relativistic velocities addition1 eg Pe=0.80.008, Pp=-0.70.03 Peff=0.9620.004 small uncertainty How to best utilize Peff? Measure: RR,LL,RL,LR Fit  Polarization Dist.

  22. Example: Polarized Protons or Deuterons (Unpolarized Electrons) C1q C2q  (1-4sin2W) Use to measure sin2W?

  23. LDRD ARL GOALS Examine Machine and Detector Requirements For 1% Include EW Radiative Corrections to DIS Is 100fb-1 Sufficient? Utility of Proton Polarization? Stage 1 e-Ion aim for 4% Study Nuclear Effects (EMC, CSV, Sum Rules) Important Secondary e-Ion Goal? Improves Proposal?

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