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Paul E. Reimer

DIS-Parity: Measuring sin 2 θ W with Parity Violation in Deep Inelastic Scattering using Baseline Spectrometers at JLab 12 GeV. Paul E. Reimer. Charge. Standard Model parameters: Charge, e , a em g , G F m lifetime. Vector: g i V = t 3L (i) – 2q i sin 2 ( q W )

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Paul E. Reimer

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  1. DIS-Parity: Measuring sin2θW with Parity Violation in Deep Inelastic Scattering using Baseline Spectrometers at JLab 12 GeV Paul E. Reimer

  2. Charge • Standard Model parameters: • Charge, e ,aem • g , GF m lifetime Vector: giV= t3L(i) – 2qi sin2(qW) Axial: giA = t3L(i) • MZ • sin2(qW) Weak isospin Weinberg-Salam model and sin2(qW) • Unification of Weak and E&M Force • SU(2)—weak isospin—Triplet of gauge bosons • U(1)—weak hypercharge—Single gauge boson • Electroweak Lagrangian: • Jm, JmYisospin and hypercharge currents • g, g0 couplings between currents and fields Gary Larson, The Far Side Remember—I’m not the expert here.

  3. Running of sin2(W) • Measurements of sin2(W) • APV Cs • Møller Scattering (SLAC E-158) • DIS (NuTeV) • Clear indication of running of sin2(W) • Future Experiments • Q-Weak (JLab) • Møller (JLab 12 GeV) • DIS-Parity at JLab 12 GeV

  4. e e DIS Formalism on unpolarized Deuterium Target Longitudinally polarized electrons on unpolarized deuterium target—Cahn and Gilman, PRD 17 1313 (1978). C1q) NC vector coupling to q £ NC axial coupling to e C2q) NC axial coupling to q £ NC vector coupling to e Cia provide sensitivity to sin2(qW) Note that each of the Cia are sensitive to different possible S.M. extensions.

  5. Gain factor of 2 in dsin2(qW) over dAd Large asymmetry Q2 = 3.7 GeV2, Ad = 0.0003 “Easy experiment” e e e e e e + ? g Z APV ~ Sensitivity to sin2(qW) Look for interference between large photon term and New Physics

  6. Q-Weak (JLab) Møller Scattering Atomic Parity Violation e g e e e e e e Z Z g g Cs133 Z g e p e • Coherent quarks in Proton • Results in ~2008 • 2(2C1u+C1d) • S Page Z • Purely Leptonic—no quark interactions • K Kumar/D. Mack n • Coherent quarks in entire nucleus • Nuclear structure uncertainties • -376 C1u – 422 C1d • A. Derevianko and Other talks n n n m Z W + How does DIS-Parity fit in? Neutrino Scattering DIS-Parity Expt. Probe different parts of Lagrangian • Quark scattering (from nucleus) • Weak charged and neutral current difference • Tim Londergan • Isoscaler quark scattering • (2C1u-C1d)+Y(2C2u-C2d) • X Zheng/P. Souder

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

  8. Criteria for DIS-Parity with baseline equipment Expt. Assumptions: • 60 cm liquid deuterium target • 11 GeV beam @ 90mA • 85% polarization § 0.5% • Rates which can be handled: • 1MHz DIS • /e ¼ 1 ) 1 MHz pions • 2 MHz Total rate General Experimental Criteria: • DIS regime: • Maximize Q2 (3.0-4.0 GeV2) • Large W2 ( > 4GeV2) • Minimize uncertainty from parton distributions: • Deuterium target (d/u ratio vs nuclear effects) • x<0.7 • Maximize sensitivity to sin2W • Large Y 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 • Pmax¼ 7.4 GeV/c §10% • W = 8.1 msr • SHMS spectrometer: • Design in progress • Pmax¼ 11 GeV § 10% •  = 5.2 msr SHMS HMS Figures from Hall C CDR

  10. JLab Hall C SHMS/HMS combination Statistical Precision • Two independent spectrometer measurements • Combined statistical precision • A/A = 0.5% • sin2W/sin2W = 0.26% What about Hall A? • Smaller solid angle and lower E0 • Ready for 11 GeV years sooner! What about systematics? • Large asymmetry (3£ 10-4) implies short runtime • 13 “perfect” days • E0 = 7 GeV (scattered electron momentum) •  = 13o General experimental criteria are met.

  11. Uncertainties in Ad • Beam Polarization: • Q-Weak also needs 1% polarization accuracy. • Hall C Møller has achieved 0.5% polarization accuracy at low intensity • Determination of Q2 significant • Higher Twist will be studied by • PV-DIS at 6 GeV • Res-Parity

  12. Expected sin2(qW) Results (JLab) dAd/Ad = §0.50% (stat) §0.58% (syst) (§ 0.78% combined) dsin2(qW)/sin2W= § 0.26% (stat) § 0.36% (sys) (§ 0.45% combined) What about Ciq’s?

  13. Extracted Signal—It’s all in the binning Fit Asymmetry data as fn. of Y A = A0 [ (2C1u – C1d) + Y(2C2u – C2d)] intercept = 2C1u – C1d (QWeak)slope = 2C2u – C2d

  14. Exp. Constraints on C1u, C1d, C2u and C2d Present experimental constraints are wide open, except for APV (1 standard deviation limits shown) Combined result significantly constrains 2C2u–C2d. PDG 2C2u–C2d = –0.08 § 0.24Combined d(2C2u–C2d) = § 0.014

  15. DIS-Parity: Conclusions • Measurements of sin2(qW) below MZ 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: d sin2(qW) = 0.0011 d(2C2u – C2d) = 0.014 Waiting for 12 GeV upgrade!

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