Gamma-Z box contributions to parity violating elastic e-p scattering

Abstract

Parity-violating (PV) elastic electron-proton scattering measures Q-weak for the proton, $Q_W^p$. To extract $Q_W^p$ from data, all radiative corrections must be well-known. Recently, disagreement on the gamma-Z box contribution to $Q_W^p$ has prompted the need for further analysis of this term. Here, we support one choice of a debated factor, go beyond the previously assumed equality of electromagnetic and gamma-Z structure functions, and find an analytic result for one of the gamma-Z box integrals. Our numerical evaluation of the gamma-Z box is in agreement within errors with previous reports, albeit somewhat larger in central value, and is within the uncertainty requirements of current experiments.

4 pages, 4 figures, v2: reference added, typo fixed

References in corpus (4)

• Parton distributions for the LHC
• New parton distributions for collider physics
• Isovector EMC effect explains the NuTeV anomaly
• The Two-Photon-Exchange and γZ-Exchange Corrections to parity-Violating Elastic Electron-Proton Scattering