Parity-Violating Møller Scattering at NNLO: Closed Fermion Loops

Abstract: A complete, gauge-invariant computation of two loop virtual corrections involving closed fermion loops to the polarized M{\o}ller scattering asymmetry is presented. The set of contributions involving two closed fermion loops and the set involving one closed fermion loop are numerically similar in magnitude to the one-loop bosonic corrections and yield an overall correction of 1.3% relative to the tree-level asymmetry. We estimate sizes of remaining two-loop contributions and discuss implications for the upcoming MOLLER experiment.