NLO radiative corrections for forward-backward and left-right asymmetries at a B-factory

Abstract

This paper presents the first calculations of the parity-violating polarization asymmetry and forwardbackward asymmetry of the eþe− → μþμ−ðγÞ process at a center-of-mass energy of 10.579 GeV with up to one-loop electroweak radiative corrections. The calculations are relevant for future precision electroweak measurements at the Belle II experiment, which is now collecting data at the SuperKEKB eþe− collider with a center-of-mass energy at the mass of the ϒð4SÞ resonance. In this paper we take under full control the bremsstrahlung process at the conditions of Belle II/SuperKEKB, and the possibilities for a soft photon approach are discussed. The scale of the obtained relative corrections to the parity-violating and forwardbackward asymmetries is significant and the scattering angle dependencies of the asymmetries is nontrivial. As an additional validation cross-check using an independent formulation, the calculated asymmetries are compared to results from the KK Monte Carlo generator.