Bosonic Contribution to Parity-Violating Møller Scattering at NNLO

Abstract

We calculate the dominant bosonic two-loop virtual electroweak corrections to parity-violating Møller scattering at low energies. The electron effective weak charge is extracted from the polarization asymmetry, retaining all contributions that are enhanced by $(1-4\sin^2θ_W)^{-1}$ or $\ln^2(M_{W,Z}^2/Q^2)$ relative to the tree-level contribution. Analytical results are obtained using the expansion by regions method in the low-energy limit $Q^2\ll M_{W,Z}^2$. Within this approximation, the dominant two-loop bosonic corrections shift the electron effective weak charge (or equivalently the polarization asymmetry) by $0.3\%$. We examine the origin of the leading contributions to this result and assess the remaining theoretical uncertainty from purely bosonic contributions for the MOLLER experiment to about 0.1%.