The Weak Charge of the Proton. A Search For Physics Beyond the Standard Model [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 539 Modern physics
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2015
• Mô tả vật lý: Size: 240 p. : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 268226
• Chủ đề: 1. 72 physics of elementary particles and fields; 2. Electron-proton interactions; 3. P invariance; 4. Protons; 5. Standard model

Tóm tắt

 The Q<
 sub>
 weak<
 /sub>
  experiment, which completed running in May of 2012 at Jefferson Laboratory, has measured the parity-violating asymmetry in elastic electron-proton scattering at four-momentum transfer Q<
 sup>
 2<
 /sup>
  =0.025 (GeV/c)<
 sup>
 2<
 /sup>
  in order to provide the first direct measurement of the proton's weak charge, Q<
 sub>
 W<
 /sub>
 <
 sup>
 p<
 /sup>
 . The Standard Model makes firm predictions for the weak charge
  deviations from the predicted value would provide strong evidence of new physics beyond the Standard Model. Using an 89% polarized electron beam at 145 microA scattering from a 34.4 cm long liquid hydrogen target, scattered electrons were detected using an array of eight fused-silica detectors placed symmetric about the beam axis. The parity-violating asymmetry was then measured by reversing the helicity of the incoming electrons and measuring the normalized difference in rate seen in the detectors. The low Q<
 sup>
 2<
 /sup>
  enables a theoretically clean measurement
  the higher-order hadronic corrections are constrained using previous parity-violating electron scattering world data. The experimental method will be discussed, with recent results constituting 4% of our total data and projections of our proposed uncertainties on the full data set.