Paul E. ReimerArgonne National Laboratory

17 January 2003

Exploring the Standard Model with JLab at 12 GeV

• Standard Model tests: Beyond sin2(W).

• e2ePV: Moller Scattering at 11 GeV

• DIS-Parity: Parity NonConserving Electron Deep Inelastic Scattering

For Dave Mack, Paul Souder, Michael Ramsey-Musolf, et al.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 2

sin2(W) measurements below Z-pole

• Atomic Parity Violation (APV):– Hard to understand theoretically.– Consistent with S.M. (plot is out of date)

Future measurements

• Qweak (Jlab)– Qweak PROTON– ¼ 2005-07

• E158-Moller– QWeak ELECTRON– Final run 2003

•e2ePV–11 GeV-Moller Scattering–Q2 = 0.008 GeV2.

•DIS-Parity–11 GeV JLab DIS Parity Violation–Q2 = 3.5 GeV2

• Standard Model predicts sin2(W) varies (runs) with Q2 – Non-S.M. physics may move measurements away from running curve.– Different measurements sensitive to different non-S.M. physics.– Well measured at Z-pole, but not at other Q2.

• NuTeV A scattering:– 3 from Standard Model!!!– Fe target: PDF’s in iron? Nuclear corrections?

17 January 2003 Paul E. Reimer, Argonne National Laboratory 3

RPVRPV

No SUSY No SUSY dark dark mattermatter

Beyond sin2(W): e.g. SUSY and Dark Matter

What is Dark Matter? •S.M.: QW

electron and QWproton both

measure 1-4sin2(W).•SUSY: Loop contributions can change this by measurable amounts!

NASA Hubble NGC3310

hep-ph/0205183

JLab QWeak (proton) and SLAC E158

Moller (QWe)

anticipated limits.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 4

e2ePV: Parity Violating Moller Scattering at 12 GeV

D. Mack, W. van Oers, R. Carlini, N. Simicevic, G. Smith

17 January 2003 Paul E. Reimer, Argonne National Laboratory 5

e2ePV: Moller Scattering at 12 GeV

• Measurement of QWeak of the electron.

• Very small asymmetry:

A|11 GeV ¼ 9¢10-7 (1 – 4 sin2W) ¼ 4¢10-8.

• Near-vanishing of the tree-level asymmetry makes this measurement sensitive to

•New physics at tree-level (e.g. Z0),•New physics via loops (e.g. SUSY loop contributions).

Restriction the available parameter space by a small amount is useful!

• Is there room for JLab to improve on the SLAC E158 measurement? What type of apparatus would be needed?

17 January 2003 Paul E. Reimer, Argonne National Laboratory 6

Moller sin2 W Error De-Magnification

sin2(W) ¼ 0.2381 - 4 sin2(W) ¼ 0.05

Radiative corrections• Not all of which are suppressed (De-Magnified) by (1-4sin2(W)• Reduce tree-level Moller asymmetry by ¼ 40%

17 January 2003 Paul E. Reimer, Argonne National Laboratory 7

Moller 12 GeV vs. 48 GeV

Repeat SLAC-E158 Moller

• Figure of merit:• A2 d/d / Ebeam.• Factor of 4 better at

SLAC.• All else equal, the

advantage goes to the higher beam energy—but “all else” is not equal!!

• JLab can have a clear advantage in luminosity.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 8

JLab 12 GeV Moller vs. SLAC E158

JLab’s advantage comes from the higher integrated luminosity available.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 9

Moller sin2(W) Anticipated Uncertainties

Clearly a competitive measurement of sin2W is possible at 11 GeV which is competitive with the best single measurements below and at the Z-pole.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 10

Moller Detection

Detector Concept:• Drift scattered electrons to a collimator.• Focus electrons in a resistive toroidal

magnet.• Drift electrons to detector ring.

Laboratory scattering angles are small!!

Detector Requirements: • Focus Moller electrons of

momentum 4.5 GeV/c § 33%.• Toroidal magnet with 1/R field is

well suited.• Field requirement are less and

scattering angle larger than at SLAC

17 January 2003 Paul E. Reimer, Argonne National Laboratory 11

e2ePV Moller Conclusions• There is a small window for

a Moller exp. at JLab to improve over SLAC E-158.

• This improvement can have a significant impact on the range of allowable SUSY extensions. RPVRPV

No SUSY No SUSY dark matterdark matter

hep-ph/0205183

JLab QWeak (proton) and JLab e2ePV

Moller (QWe)

anticipated limits.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 12

DIS-Parity: Polarized e- deuterium Deep Inelastic Scattering Parity

NonConservation

Paul Reimer, Peter Bosted, Dave Mack

17 January 2003 Paul E. Reimer, Argonne National Laboratory 13

Textbook Physics: Polarized e- d scattering

Repeat SLAC experiment (30 years later) with better statistics and systematics at 12 GeV Jefferson Lab:

• Beam current 100 A vs. 4 A at SLAC in ’78 £ 25 stat• 60 cm target vs. 30 cm target £ 2 stat• Pe (=electron polarization) = 80% vs. 37% £ 4 stat• Pe ¼ 1% vs. 6% £ 6 sys

17 January 2003 Paul E. Reimer, Argonne National Laboratory 14

DIS-Parity: Polarized e- deuterium DISLongitudinally polarized electrons on unpolarized isoscaler (deuterium) target.

Note that each of the Cia are sensitive to different possible S.M.

extensions.

C1q ) NC vector coupling to q £ NC axial coupling to eC2q ) NC axial coupling to q £ NC vector coupling to e

17 January 2003 Paul E. Reimer, Argonne National Laboratory 15

DIS-Parity: Detector and Expected Rates• Expt. Assumptions:

– 60 cm ld2/lH2 target– 11 GeV beam @ 90– 75% polar.– 12.5± central angle– 12 msr d– 6.8 GeV§10% mom. bite

• Rate expectations:– ¼ 1MHz DIS– /e ¼ 1 ) 1 MHz pions– 2 MHz Total rate– dA/A = 0.5% ) 2 weeks

(ideal) plus time for H2 and systematics studies.

Will work in either Hall C (HMS +SHMS) or Hall A (MAD)

hxi = 0.45 hQ2i = 3.5 GeV2

hYi = 0.46 hW2i = 5.23 GeV2

Q2 near NuTeV result—provide cross check on neutrino result.

17 January 2003 Paul E. Reimer, Argonne National Laboratory 16

Uncertainties in Ad• Beam Polarization:

–This drives the uncertainty!–QWeak also needs 1.4% –Hall C Moller claims 0.5%.

• Higher twists may enter at low Q2:–This could be a problem.–Check by taking additional data at lower and higher Q2.

–Possible 6 GeV experiment?

• Ad to § 0.5% stat § 1.1% syst.

(1.24% combined)

Statistical (2 weeks) 0.5%

Beam polarization 1.0%

Q2 0.5%

Radiative corr. <1%

R = (L/T) = § 15% <0.02%

s(x) = § 10% <0.03%

EMC Effect ????

Higher Twist ????

What about Ciq’s?

17 January 2003 Paul E. Reimer, Argonne National Laboratory 17

Extracted Signal—It’s all in the binning

Note—Polarization uncertainty enters as in slope and intercept

Aobs = PAd / P(2C1u–C1d) + P(2C2u–C2d)Y]

but is correlated

PDG: C1u= –0.209§0.041 highlyC1d= 0.358§0.037

correlated

2C2u– C2d = –0.08§0.24

This measurement:

(2C1u– C1d) = 0.005 (stat.)

(2C2u– C2d) = 0.014 (stat.)

17 January 2003 Paul E. Reimer, Argonne National Laboratory 18

DIS-Parity determines 2C2u-C2d

Combined result significantly constrains 2C2u–C2d. PDG 2C2u–C2d = –0.08 § 0.24 Combined (2C2u–C2d) = § 0.014

£ 17 improvement (S.M 2C2u – C2d = 0.0986)

17 January 2003 Paul E. Reimer, Argonne National Laboratory 19

DIS-Parity: Conclusions

• DIS-Parity Violation measurements can easily accomplished at JLab with the 12 GeV upgrade (beam and detectors) in either Hall A or Hall C.

• Large asymmetry/quick experiment.• Requires very little beyond the

standard equipment which will already be present in the halls.

• Near NuTeV Q2.

• Higher twist may be important

(2C1u – C1d) = 0.005(2C2u – C2d) = 0.014

17 January 2003 Paul E. Reimer, Argonne National Laboratory 20

JLab tests of the Standard Model • Measurements of sin2(W) below MZ

provide strict tests of the SM.• Measurements in different systems

provide complementary information.• Moller Parity Violation can be measured

at JLab at a level which will impact the Standard Model.

• DIS-Parity violation measurement is easily carried out at JLab.

RPVRPV

No SUSY No SUSY dark matterdark matter

hep-ph/0205183

Weak Mixing Angle MS-bar schemeJens Erler