Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring the Weak Charge of the Proton via Elastic Electron-Proton
  Scattering   The Qweak experiment which ran at Jefferson Lab in Newport News, VA, measured
the weak charge of the proton $Q_W^p$ via elastic electron-proton scattering.
Longitudinally polarized electrons were scattered from an unpolarized liquid
hydrogen target. The Standard Model predicts a small parity-violating asymmetry
of scattering rates between electron right and left helicity states due to the
weak interaction. An initial result using 4% of the data was published in
October 2013 with a measured parity-violating asymmetry of $-279\pm
35(\text{stat})\pm 31$ (syst) parts per billion (ppb). This asymmetry, along
with other data from parity-violating electron scattering experiments, provided
the world's first determination of the weak charge of the proton. The weak
charge of the proton was found to be $Q_W^p=0.064\pm0.012$, in agreement with
the Standard Model prediction of $Q_W^p(SM)=0.0708\pm0.0003$.
  The results of the full dataset are expected to decrease the statistical
error from the initial publication by a factor of 4-5. The level of precision
of the final result makes it a useful test of Standard Model predictions and
particularly of the "running" of $\sin^2\theta_W$ from the Z-mass to low
energies. This thesis focuses on reduction of systematic error in two key
systematics for the Qweak experiment. First, techniques for measuring and
removing false asymmetries arising from helicity-correlated electron beam
properties at the few ppb level are discussed. Second, as a parity-violating
experiment, Qweak relies on accurate knowledge of electron beam polarimetry. To
help address the requirement of accurate polarimetry, a Compton polarimeter
built specifically for Qweak. Compton polarimetry requires accurate knowledge
of laser polarization inside a Fabry-Perot cavity enclosed in the electron beam
pipe. A new technique was developed for Qweak that nearly eliminates this
systematic error.

32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph