DIS-Parity: Measuring sin 2 θ W with Parity Violation in Deep Inelastic Scattering using Baseline Spectrometers at JLab 12 GeV Paul E. Reimer

2 Unification of Weak and E&M Force SU(2)—weak isospin—Triplet of gauge bosons U(1)—weak hypercharge—Single gauge boson Electroweak Lagrangian: J , J  Y  isospin and hypercharge currents g, g 0 couplings between currents and fields Weinberg-Salam model and sin 2 (  W ) Remember—I’m not the expert here. Gary Larson, The Far Side Vector: g i V = t 3L (i) – 2q i sin 2 (  W ) Axial: g i A = t 3L (i) Charge Weak isospin Standard Model parameters: Charge, e,  em g, G F  lifetime M Z sin 2 (  W )

3 Running of sin 2 (  W ) Measurements of sin 2 (  W ) –APV Cs –Møller Scattering (SLAC E-158) – DIS (NuTeV) Clear indication of running of sin 2 (  W ) Future Experiments –Q-Weak (JLab) –Møller (JLab 12 GeV) DIS-Parity at JLab 12 GeV

4 DIS Formalism on unpolarized Deuterium Target Note that each of the C ia are sensitive to different possible S.M. extensions. Longitudinally polarized electrons on unpolarized deuterium target—Cahn and Gilman, PRD (1978). C 1q ) NC vector coupling to q £ NC axial coupling to e C 2q ) NC axial coupling to q £ NC vector coupling to e C ia provide sensitivity to sin 2 (  W ) e e

5 Sensitivity to sin 2 (  W ) Large asymmetry Q 2 = 3.7 GeV 2, A d = “Easy experiment” Gain factor of 2 in  sin 2 (  W ) over  A d Look for interference between large photon term and New Physics A PV ~ ee  e ? e + ee Z

6 How does DIS-Parity fit in? ee  Z p n  W Z + ee  e e Z Møller Scattering Purely Leptonic—no quark interactions K Kumar/D. Mack ee  Z Q-Weak (JLab) Coherent quarks in Proton Results in ~2008 2(2C 1u +C 1d ) S Page e  Z Cs 133 Atomic Parity Violation Coherent quarks in entire nucleus Nuclear structure uncertainties -376 C 1u – 422 C 1d A. Derevianko and Other talks DIS-Parity Neutrino Scattering Isoscaler quark scattering (2C 1u -C 1d )+Y(2C 2u -C 2d ) X Zheng/P. Souder Quark scattering (from nucleus) Weak charged and neutral current difference Tim Londergan Expt. Probe different parts of Lagrangian

7 Jefferson Lab at 12 GeV Upgrade Currently: 6 GeV CW beam 3 exp. Halls (A, B, C) 80% polarized beam Upgrade (Completion date?): 12 GeV (11 GeV to Hall A, B, C) Addition of Hall D 85  A to Hall A, C Figures from JLab web site

8 Criteria for DIS-Parity with baseline equipment General Experimental Criteria: DIS regime: –Maximize Q 2 ( GeV 2 ) –Large W 2 ( > 4GeV 2 ) Minimize uncertainty from parton distributions: –Deuterium target (d/u ratio vs nuclear effects) –x<0.7 Maximize sensitivity to sin 2  W –Large Y Expt. Assumptions: 60 cm liquid deuterium target 11 GeV 90mA 85% polarization § 0.5% Rates which can be handled: –1MHz DIS –  /e ¼ 1 ) 1 MHz pions –2 MHz Total rate Implementation  /e separation ) gas Cherenkov counters ¼ 6 GeV thresh. Rate requires flash ADC’s or Scaler-based DAQ on Cherenkov and Calorimeters—this is a counting experiment!!

9 Hall C at 11 GeV HMS spectrometer P max ¼ 7.4 GeV/c § 10%  = 8.1 msr SHMS spectrometer: Design in progress P max ¼ 11 GeV § 10%  = 5.2 msr Figures from Hall C CDR HMS SHMS

10 JLab Hall C SHMS/HMS combination Large asymmetry (3£ ) implies short runtime 13 “perfect” days E 0 = 7 GeV (scattered electron momentum)  = 13 o AverageRange x Y Q2Q2 3.9 GeV GeV 2 W2W2 4.7 GeV GeV 2 General experimental criteria are met. Statistical Precision Two independent spectrometer measurements Combined statistical precision –  A/A = 0.5% –  sin 2  W /sin 2  W = 0.26% What about Hall A? Smaller solid angle and lower E 0 years Ready for 11 GeV years sooner! What about systematics?

11 Uncertainties in A d Beam Polarization: –Q-Weak also needs 1% polarization accuracy. –Hall C Møller has achieved 0.5% polarization accuracy at low intensity Determination of Q 2 significant Higher Twist will be studied by –PV-DIS at 6 GeV –Res-Parity SourceUncertainty Source AA  sin 2  W Statistical0.5%0.26% Beam polarization0.5%0.26% Deadtime0.3%0.15% Q2Q2 0.2%  R =  (  L /  T ) 0.01% Parton Distributions 0.05% Radiative corr.?? Higher 6GeV Res-Parity EMC/Nuclear Effects in 2 H Parity Violation Res-Parity Total Uncertainty0.8%0.45%

12 Expected sin 2 (  W ) Results (JLab)  A d /A d = § 0.50% (stat) § 0.58% (syst) ( § 0.78% combined)  sin 2 (  W )/sin 2  W = § 0.26% (stat) § 0.36% (sys) ( § 0.45% combined) What about C iq ’s?

13 Extracted Signal—It’s all in the binning Fit Asymmetry data as fn. of Y A = A 0 [ (2C 1u – C 1d ) + Y(2C 2u – C 2d )] intercept = 2C 1u – C 1d (QWeak) slope = 2C 2u – C 2d

14 Exp. Constraints on C 1u, C 1d, C 2u and C 2d Present experimental constraints are wide open, except for APV (1 standard deviation limits shown) Combined result significantly constrains 2C 2u –C 2d. PDG 2C 2u –C 2d = –0.08 § 0.24 Combined  (2C 2u –C 2d ) = § 0.014

15 DIS-Parity: Conclusions Measurements of sin 2 (  W ) below M Z provide strict tests of the Standard Model. DIS-Parity provides complementary sensitivity to other measurements. DIS-Parity Violation measurements can be carried out in at Jefferson Lab –Asymmetry is Large! Jefferson Lab:  sin 2 (  W ) =  (2C 2u – C 2d ) = Waiting for 12 GeV upgrade!