electroweak physics at the eic 1. weak nc parity violation and new physics
DESCRIPTION
Electroweak Physics at the EIC 1. WEAK NC PARITY VIOLATION AND NEW PHYSICS i) APV vs Pol Electron Scattering (A RL ) ii) QWEAK(ep), Moller(ee), DIS(eN eX) , … 2. Preliminary EIC requirements - PowerPoint PPT PresentationTRANSCRIPT
Electroweak Physics at the EIC
1. WEAK NC PARITY VIOLATION AND NEW PHYSICS
i) APV vs Pol Electron Scattering (ARL) ii) QWEAK(ep), Moller(ee), DIS(eNeX), … 2. Preliminary EIC requirements
For Competitive ARL Program ~100fb-1 (K. Kumar et al.; R. Holt) eg 1034cm-2s-1x107s William J. Marciano
Oct 21, 2009
BNL LDRD FY2010 (Funded)Electroweak Physics with an Electron-Ion Collider
Deshpande, Kumar, Marciano, Vogelsang
STUDY GOALS
• DIS & Nuclear Structure Functions (,Z,W) (Beyond HERA) L(HERA)=1031cm-2s-1 >1033cm-2s-1
• ARL, sin2W(Q2), Radiative Corrections, “New Physics” requires roughly 100fb-1(1034cm-2s-1)• Lepton Flavor Violation: eg epX requires roughly one inverse attobarn=1000fb-1! To be competitive with BR(eX)~10-10
Rates & Backgrounds Need Thorough Study
SOME ISSUES
What are the Machine and Detector Requirements?
“New Physics Effects” (Z’, Leptoquarks, SUSY, S&T, LFV…)
sin2W(Q2) Running Weak Mixing Angle
Inclusion of Electroweak Radiative Corrections (Important?)
High Precision & Polarization(0.5%?, 0.25%?)
Nucleon vs Nuclear Asymmetries (EMC Effect, CSV?)
Proton & Deuteron Polarization (Spin Content-Peff?)
Various Issues That Need Thorough Study
1) PV Weak Neutral Currents (Past, Present and Future)
• The SU(2)LxU(1)Y Weinberg-Salam Model: weak neutral current coupling
g/cosWZf(T3f-2Qfsin2W -T3f5)f
T3f=1/2, Qf=electric charge
A New Form of Parity Violation!
-Z Interference Parity Violation Everywhere!
Depends on sin2W
Atomic Parity Violation (APV)
• QW(Z,N) =Z(1-4sin2W)-N Weak Charge
W=Weak Mixing Angle
QW(p)=1-4sin2W0.08
QW(209Bi83) = -43 -332sin2W =-126 Bi Much Larger but Complicated Atomic Physics Originally APV not seen in Bi SM Ruled Out? (Later seen: Tl, Bi, Cs…)
QW(133Cs55)=-23-220sin2W
=-73.16(34) Recent(2008) Atomic Theory Improvement
1978 SLAC Polarized DIS eD Asymmetry (Prescott, Hughes…) e+De+X -Z Interference
ARL= R-L/R+L2x10-4Q2GeV-2(1-2.5sin2W) ~10-4Expected
Exp. Gave ARLexp=1.5x10-4sin2W=0.21(2)
Confirmed SU(2)LxU(1)Y SM!
±10% Determination of sin2W Precision!
Seemed to agree with GUTS (SU(5), SO(10)…)
sin2W=3/8 at unification =mX2x1014GeV
sin2W(mZ)MS=3/8[1-109/18ln(mX/mZ)+…] 0.21! (Great Desert?)
But later, minimal SU(5) ruled out by proton decay
exps (pe+)>1033yr mX>5x1015GeV
SUSY GUT UnificationmX1016GeV p1035yr
For mSUSY(TeV)
sin2W(mZ)MS=0.232 (Good Current Agreement!)
1980s - Age of EW Precision
sin2W needed better than 1% determination Renormalization Prescription Required EW Radiative Corrections Computed
Finite and Calculable: DIS N, ve, APV (A. Sirlin &WJM)
mZ, mW, Z, ALR, AFB
Define Renormalized Weak Mixing Angle: sin2WR
sin20W=1-(m0
W/m0Z)2=(e0/g0)2 Natural Bare Relation
sin2W1-(mW/mZ)2 On Shell Definition, Popular in1980s
Induces large (mt/mW)2 corrections Now Largely Abandoned
sin2W()MSe2()MS/g2()MS Good for GUT running No Large RC Induced
Theoretically Nice/ But Unphysical
sin2Wlep = Z coupling at the Z pole
very popular at LEP
= sin2W(mZ)MS+0.00028 (best feature)
sin2W(Q2) = Physical Running Angle Continuous Incorporates Z mixing loops: quarks, leptons, W
Precision measurements at the Z Pole (e+e-Zff) Best Determinations
sin2W(mZ)MS = 0.23070(26) ALR(1-4sin2W) (SLAC)
sin2W(mZ)MS = 0.23193(29) AFB(bb) (CERN) (3 sigma difference!)
World Average: sin2W(mZ)MS=0.23125(16) IS IT CORRECT?
•
-1=137.035999, G=1.16637x10-5Gev-2, mZ=91.1875GeV
+ mW=80.398(25)GeVsin2W(mZ)MS = 0.23104(15)
Implications: 114GeV<mHiggs<150GeV.
New Physics Constraints From: mW, sin2W, ,& G
S=ND/6 (ND=# of heavy new doublets, eg 4th generationND=4)
mW*= Kaluza-Klein Mass (Extra Dimensions)
GG(1+0.0085S+O(1)(mW/mW*)2+…) sin2W(mZ)MS S ND&mW*
Average 0.23125(16) +0.11(11) 2(2), mW*3TeV
ALR 0.23070(26) -0.18(15) (SUSY)
AFB(bb) 0.23193(29) +0.46(17) 9(3)! Heavy Higgs, mW*~1-2TeV
Very Different Interpretations. We failed to nail sin2W(mZ)MS!
What about low energy measurements?
• DIS Scattering: R(NX)/(NX)
Loop Effects mt heavy! (Currently 173GeV)
Early sin2W(mZ)MS=0.233SUSY GUTS
NuTeV sin2W(mZ)MS=0.236(2) High?
Nuclear-Charge Symmetry Violation?
Radiative Corrections?
Other?
Atomic Parity Violation Strikes Back
1990 QW(Cs)exp=-71.04(1.38)(0.88) C. Wieman et al.
Electroweak RCQW(Cs)SM=PV(-23-220PV(0)sin2W(mZ)MS) =-73.19(3)
1999 QW(Cs)exp=-72.06(28)(34) Better Atomic Th.
2008 QW(Cs)exp=-72.69(28)(39)sin2W(mZ)MS=0.2290(22)
2009 QW(Cs)exp=-73.16(28)(20)sin2W(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=0.00.4 mZ>1.2TeV, leptoquarks, Anapole Moment …
Radiative Corrections to APV (eN Interaction)
QW(Z,N)= PV(-N+Z(1-4PVsin2W(mZ)MS)
PV=1-/2(1/s2+4(1-4s2)(ln(mZ/M)2+3/2)+….)0.99
PV(0)=1-/2s2((9-8s2)/8s2+(9/4-4s2)(1-4s2)(ln(mZ/M)2+3/2)
-2/3(T3fQf-2s2Qf2)ln(mZ/mf)2+…)1.003
s2sin2W(mZ)MS=0.23125, M=Hadronic Mass Scale
Radiative Corrections to APV small & insensitive to hadronic unc.
Same Corrections Apply to elastic eN scattering as Q20, Ee<<mN
E158 at SLAC Pol eeee Moller)Ee50GeV on fixed target, Q2=0.02GeV2
ALR(ee)=-131(14)(10)x10-9 (1-4sin2W)
EW Radiative Corrections -50%! (Czarnecki &WJM)
Measured to 12% sin2W to 0.6%
sin2W(mZ)MS=0.2329(13) slightly high
Best Low Q2 Determination of sin2W
APV(Cs) & E158 sin2W(Q2) running
ALR(ee)exp=ALR(ee)SM(1+0.24T-0.33S+7(mZ/mZ)2…)
Constrains “New Physics” eq mZ>0.6TeV, H--,S, Anapole Moment, …
Goals of Future Experiments
• High Precision: sin2W0.00025 or better
• Low Q2 Sensitivity to “New Physics”
mZ’ >1TeV, S<0.1-0.2, SUSY Loops, Extra Dim., Compositeness….
Future Efforts
QWEAK exp at JLAB being prepared
Will measure forward ALR(epep) (1-4sin2W)=QW(p)
E=1.1GeV, Q20.03GeV2, Pol=0.801%ARL(ep)3x10-7
small ARL requires long running
Goal sin2W(mZ)MS=0.0008 via 4% measurement of ALR
Will be best low energy measurement of sin2W
ALR(ep)exp=ALR(ep)SM(1+4(mZ/mZ)2+…)
eg mz~0.9TeV Sensitivity (Not as good as APV)
• The Gorchtein - Horowitz Problem (PRL)
Z box diagrams: O(2Ee/mp) 6% of QW(p)!
RC Estimate needs to be checked
Proposed Qweak Theory Uncertainty < 2%?
JLAB Flagship Experiment
Future Efforts: Polarized Moller at JLAB
After 12GeV Upgrade ALR(eeee) to 2.5%
sin2W(mZ)MS=0.00025! Comparable to Z pole studies!
ALR(ee)exp=ALR(ee)SM(1+7(mZ/mZ)2+…)
Explores mZ1.5TeV Better than APV, S0.08 etc.
Future JLAB Flagship Experiment (difficult!) Complementary to LHC Discoveries
Comparison of QW(p) & QW(Cs)
• HPV=G/2[(C1uuu+C1ddd)e5e+
(C2uu5u+C2dd5d)ee+…]
QW(p)=2(2C1u+C1d)
QW(Cs)=2(188C1u+211C1d)
What about the C2q?
What About C2u and C2d?
• Renormalized at low Q2 by Strong Interactions
Measure in Deep-Inelastic Scattering (DIS), eD & ep
ARL(eDeX)2x10-4GeV-2Q2[(C1u-C1d/2)+f(y)(C2u-C2d/2)]
f(y)=[1-(1-y)2]/[1+(1-y)2]
Standard Model: C1u= (1-8sin2W/3)/2 0.20
C1d=-(1-4/sin2W/3)/2 -0.32
C2u= (1-4sin2W)/2 0.04
C2d =-(1-4sin2W)/2-0.04
C2q sensitive to RC & “New Physics” eg Z (SO(10))
Measure ARL to 0.25%?
Measure C2q to 1-2%? Theory (loops)?
JLAB 6 GeV DIS eDeX On the books
JLAB 12 GeV DIS eD Proposed (Likely)
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, AQ2, N1/Q2 (acceptance?)
High Q2 Better (but Collider Luminosity?)
K. Kumar Talk 100fb-1 Needed
Program can be started with lower luminosity
Do DIS ep, eD, eN at factor of 10 lower
Single and Double Polarization Asymmetries
Polarized e: AeRL=(RR+RL-LR-LL)/(RR+RL+LR+LL)Pe
Polarized p: ApRL=(RR+LR-RL-LL)/(RR+LR+RL+LL)Pp
Polarized D: Pu=Pd=PD
Use to determine quark polarizations
Polarized e&p or D AepRRLL= (RR-LL)/(RR+LL)Peff
Peff=(Pe+Pp)/(1+PePp) like relativistic velocities addition1
eg Pe=0.85, Pp=0.70 Peff=0.972!
uncertainty: Peff/Peff=0.17Pe/Pe+0.08Pp/Pp small
If we determine (see above) Pp=0.700.014
Peff=0.9720.0018 Superb!
How to best utilize Peff?
Preliminary Comments
Use polarized e & polarized p or D at EICARR,LLto 0.25%
Systematics?
Peff determined to 0.1-0.2% via ApRL & AD
RL (possible?)
Other?
ADRR,LL(1-3.2sin2W) sin2W/sin2W=-0.4AD
RR.LL/ADRR.LL
0.25% measurement of ADRR.LLsin2W=0.00023
Sensitive to “New Physics” eg S=0.05
Summary: Measure DIS RR, RL, LR, LL
Determine: Pquarks, Peff. sin2W precisely
LDRD ARL GOALS
Elucidate Physics Case
Examine Machine and Detector Requirements For 0.1%
sin2W Determination
Include Full EW Radiative Corrections to DIS
Is 100fb-1 Sufficient? Doable?
Utility of Proton (Deuteron) Polarization? Precision sin2W
Stage 1 e-Ion Goals?
Study Pol. Quark dist. & Nuclear Effects (EMC, CSV)
Important Secondary EIC Goal? Expands Proposal?