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 )
Paul E. Reimer
Vector: giV= t3L(i) – 2qi sin2(qW)
Axial: giA = t3L(i)
Weak isospinWeinberg-Salam model and sin2(qW)
Gary Larson, The Far Side
Remember—I’m not the expert here.
eDIS 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.
Atomic Parity Violation
+How does DIS-Parity fit in?
Expt. Probe different parts of Lagrangian
Figures from JLab web site
General Experimental Criteria:
(d/u ratio vs nuclear effects)
Figures from Hall C CDR
What about Hall A?
What about systematics?
(scattered electron momentum)
General experimental criteria are met.
dAd/Ad = §0.50% (stat)
(§ 0.78% combined)
dsin2(qW)/sin2W= § 0.26% (stat)
§ 0.36% (sys)
(§ 0.45% combined)
What about Ciq’s?
Fit Asymmetry data as fn. of Y
A = A0 [ (2C1u – C1d) + Y(2C2u – C2d)]
intercept = 2C1u – C1d (QWeak)slope = 2C2u – 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
d sin2(qW) = 0.0011
d(2C2u – C2d) = 0.014
Waiting for 12 GeV upgrade!