Partonic calculation of Z Exchange Corrections to Parity-Violating Elastic Electron-Proton Scattering
(Dated: March 7, 2009)We calculate γZ exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a parton model using the formalism of generalized parton distributions(GPDs).We also examine the validity of the zero-momentum-transfer approximation adopted in the litera-tures and ﬁnd that it overestimates the γZ exchange eﬀect signiﬁcantly at the forward scatteringangles.