Parity-Violating and Parity-Conserving Asymmetries in \boldmath$\vec{e}p$ and \boldmath$\vec{e}N$ Scattering in the Qweak Experiment

ORAL

Abstract

The Qweak experiment at Jefferson Lab has made the first determination of the weak charge of the proton in elastic scattering of longitudinally polarized electrons from unpolarized protons at a momentum transfer $Q^2$ of 0.025 (GeV/c)$^2$. To achieve the required precision to measure the small parity-violating asymmetry of -279 parts per billion, we directed a 180 $\mu$A 85\%-polarized electron beam on a 35 cm long liquid hydrogen target and integrated scattered events in eight azimuthally symmetric fused silica Cerenkov detectors. Based on 4\% of the total data collected by the experiment, we find a value for the weak charge of proton in agreement with predictions of the Standard Model. To correct for the contributions from background processes, we conducted several additional parity-violating and parity-conserving asymmetry measurements with different kinematics (elastic and $N \to \Delta$), electron polarization (longitudinal and transverse), and targets (protons, electrons, aluminum, and carbon). In many cases, these ancillary results are first or high-precision measurements as well. I will discuss the analysis and results of the main experiment with a focus on several of the ancillary results.

Authors

  • Wouter Deconinck

    College of William \& Mary