Physics – Nuclear Physics – Nuclear Theory
Scientific paper
2011-02-18
Phys.Rev.C84:015502,2011
Physics
Nuclear Physics
Nuclear Theory
25 pages, 17 figures, 4 tables; revised version accepted for publication in PRC
Scientific paper
10.1103/PhysRevC.84.015502
We analyze the dispersion correction to elastic parity violating electron-proton scattering due to $\gamma Z$ exchange. In particular, we explore the theoretical uncertainties associated with modeling contributions of hadronic intermediate states. Taking into account constraints from low- and high-energy, parity-conserving electroproduction measurements, choosing different models for contributions from the non-resonant processes, and performing the corresponding flavor rotations to obtain the electroweak amplitude, we arrive at an estimate of the uncertainty in the total contribution to the parity-violating asymmetry. At the kinematics of the Q-Weak experiment, we obtain a correction to the asymmetry equivalent to a shift in the proton weak charge of $(0.0054\pm0.0020)$. This should be compared to the value of the proton's weak charge of $\qwp=0.0713\pm0.0008$ that includes SM contributions at tree level and one-loop radiative corrections. Therefore, we obtain a new Standard Model prediction for the parity-violating asymmetry in the kinematics of the Q-Weak experiment of $(0.0767\pm0.0008\pm0.0020_{\gamma Z})$. The latter error leads to a relative uncertainty of 2.8% in the determination of the proton's weak charge, and is dominated by the uncertainty in the isospin structure of the inclusive cross section. We argue that future parity-violating inelastic $ep$ asymmetry measurements at low-to-moderate $Q^2$ and $W^2$ could be exploited to reduce the uncertainty associated with the dispersion correction. Because the corresponding shift and error bar decrease monotonically with decreasing beam energy, a determination of the proton's weak charge with a lower-energy experiment or measurements of "isotope ratios" in atomic parity-violation could provide a useful cross check on any implications for physics beyond the Standard Model derived from the Q-Weak measurement.
Gorchtein Mikhail
Horowitz Charles J.
Ramsey-Musolf Michael. J.
No associations
LandOfFree
Model-dependence of the $γZ$ dispersion correction to the parity-violating asymmetry in elastic $ep$ scattering does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Model-dependence of the $γZ$ dispersion correction to the parity-violating asymmetry in elastic $ep$ scattering, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Model-dependence of the $γZ$ dispersion correction to the parity-violating asymmetry in elastic $ep$ scattering will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-158996