Mixed QCD-electroweak O (αsα) corrections to Drell-Yan processes in the resonance region: Pole approximation and non-factorizable corrections

Drell-Yan-like W-boson and Z-boson production in the resonance region allows for high-precision measurements that are crucial to carry experimental tests of the Standard Model to the extremes, such as the determination of the W-boson mass and the effective weak mixing angle. In this article, we establish a framework for the calculation of the mixed QCD-electroweak O(alpha(s)alpha) corrections to Drell-Yan processes in the resonance region, which are one of the main remaining theoretical uncertainties. We describe how the Standard Model prediction can be successfully performed in terms of a consistent expansion about the resonance poles, which classifies the corrections in terms of factorizable and non-factorizable contributions. The former can be attributed to the W/Z production and decay subprocesses individually, while the latter link production and decay by soft-photon exchange. At next-to-leading order we compare the full electroweak corrections with the pole-expanded approximations, confirming the validity of the approximation. At O(alpha(s)alpha), we describe the concept of the expansion and explicitly give results on the non-factorizable contributions, which turn out to be phenomenologically negligible. Our results, thus, demonstrate that for phenomenological purposes the O(alpha(s)alpha) corrections can be factorized into terms associated with initial-state and/or final-state corrections. Moreover, we argue that the factorization properties of the non-factorizable corrections at O(alpha(s)alpha) from lower-order O(alpha(s)) graphs generalize to any order in O(alpha(n)(s)alpha). (C) 2014 The Authors. Published by Elsevier B.V.