On the two-boson exchange corrections to parity-violating elastic electron-proton scattering

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The details of the calculation of the two-boson exchange effects in the parity-violating elastic ep scattering within a simple hadronic model, including both the nucleon and Δ(1232)-resonance intermediate states, are presented. We examine the sensitivity of our results with respect to choice of form factors. We emphasize the importance to use correct relations relating N to Δ and Δ to N transition vertex functions. The NΔ Coulomb quadrupole transition is found to play important role at higher Q²≥ 3.0 GeV². We also elucidate the relation between our results and the well-known result on the γZE effect given by Marciano and Sirlin (MS). The effect of the nucleon contribution δₙ to parity-asymmetry APV, is found to be in general, larger than the corresponding Δ contribution δΔ except at extreme forward angles. The corrections to the extracted values of the strange form factors Gˢₑ+βGˢₘ from the HAPPEX, A4, and G0 data are also presented. The total TBE corrections to the extracted values of Gˢₑ+βGˢₘ in recent experiments of HAPPEX G0, and A4 are, depending on kinematics, found to be small except in a few cases where they range from -20.6% to 48.3 %.