Radiative Corrections, New Physics Fits and e+e-->?->ffbar

Abstract

This document reviews the general approach to correcting the process e+e-->X->ffbar for radiative effects, where X represents an exchanged gauge boson arising from some new physics. The validity of current methods is discussed in the context of the differential cross section. To this end the universality of the dominant QED radiative corrections to such a process is discussed and an attempt is made to quantify it. The paper aims to justify, as much as possible, the general approach taken by e+e- collider experiments to the issue of how to treat the dominant radiative corrections in fitting models of new physics using inclusive and exclusive cross section measurements. We conclude that in all but the most pathological of new physics models the dominant radiative corrections (QED) to the tree level processes of the standard model can be expected to hold well for new physics. This argument follows from the fact that the phase space of indirect new physics searches is generally restrictive (high s' events) in such a way that the factorization of radiative corrections is expected to hold well and generally universal infrared corrections should be prevalent.