electroweak physics at the eic 1. weak nc parity violation and new physics

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?