Document Type

Article

Department/Program

Physics

Pub Date

3-2014

Publisher

EPJ Web of Conferences

Volume

66

Sponsorship / Conference

EPJ Web of Conferences

Creative Commons License

Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.

Abstract

A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ~ep scattering to provide the first determination of the proton’s weak charge Q p w. The experiment employed a 180 µA longitudinally polarized 1.16 GeV electron beam on a 35 cm long liquid hydrogen target. Scattered electrons in the angular range 6◦ < θ < 12◦ corresponding to Q2 = 0.025 GeV2 were detected in eight Cerenkov detectors arrayed symmetrically around the beam axis. The goals of the experiment were to provide a measure of Q p w to 4.2% (combined statistical and systematic error), which implies a measure of sin2 (θw) at the level of 0.3%, and to help constrain the vector weak quark charges C1u and C1d. The experimental method is described, with particular focus on the challenges associated with the world’s highest power LH2 target. The new constraints on C1u and C1d provided by the subset of the experiment’s data analyzed to date will also be shown, together with the extracted weak charge of the neutron.

DOI

https://doi.org/10.1051/epjconf/20146605002

Download

Share Feedback

Included in

Physics Commons

Share

COinS