Measurements of Parity-Violating Asymmetries in Electron-Deuteron Scattering in the Nucleon Resonance Region

Abstract

We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5-6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the ∆(1232). They provide a verification of quark-hadron duality -the equivalence of the quark-and hadron-based pictures of the nucleon -at the (10-15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak γZ interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.

Parity Violation Deep Inelastic Scattering Experiments at JLab

“…The electrons were scattered off of a 20-cm long liquid deuterium target, which was controlled at a temperature of 22 K. The scattered electrons were detected in a pair of spectrometers [5] that provided high precision measurements of their momentum and angle. For a significant amount of the run period, the spectrometers were set to detect DIS electrons [6]; however, additional data were also collected in four kinematic settings, which covered the entire nucleon resonance region [7]. These data provide constraints on nucleon resonance models, and for the first time, they also exhibited a feature known as "quark-hadron duality" [8] of electroweak observables.…”

“…A summary of the measured asymmetries with detailed kinematics and corrections can be found in Table I of Ref. [7]. Figure 3 displays the measured PV asymmetries, scaled by 1/Q 2 , from e-2 H scattering in the resonance region versus W .…”

Charged current semi-inclusive deeply inelastic scattering at the Electron-Ion Collider

“…Under the one photon approximation condition, the electromagnetic interaction can be described accurately which results in the straightforward interpretation of experiment data. In addition to the electromagnetic interaction, weak interaction in the scattering process provides more physical information, e.g., parity violating asymmetry [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. Comparing to the neutral current (NC) SIDIS process which propagate with γ * and/or Z 0 boson, data from the charged current (CC) experiments provide more complementary information on the partonic structure of nucleons as they probe combinations of quark flavors different from those accessible in NC ones.…”

Simple modification of Compton polarimeter to redirect synchrotron radiation

“…Recent operation at an electron beam energy of 6 GeV [4] showed a marked reduction in the polarimeter precision due to the need for thicker shielding. The filters were sufficient in the lower-energy cases but even 5 mm would allow far too many moderate energy photons through when running an 11 GeV beam, illustrating the need for reducing the SR flux incident on the photon detector through another technique.…”

“…2. The synchrotron radiation spectra in the Compton photon detector, modeled for conditions during two completed experiments, HAPPEX III [3] and PVDIS [4], are compared to the spectrum obtained from modeling the 1. fixed periods of time [5], which avoid significant systematic uncertainties in calibrating the effects of a trigger threshold, require well-understood detector response even to low energies in the Compton spectrum. While the Compton spectrum is boosted to higher energy with higher beam energy (up to a few GeV for 11 GeV beam operation, compared to 600 MeV for 6 GeV beam), the energy endpoint and intensity of the SR spectrum rises more quickly.…”