Isolated hard photon radiation in multijet production at LEP

Abstract

We present a detailed, quantitative analysis of isolated hard photon radiation in multiparton final states at LEP energies. Since a perfectly isolated photon is not an infrared safe quantity different definitions of an “isolated photon” can influence the relative production rates for photon plus jets events. We argue that there is no obvious discrepancy between recent experimental measurements and the theoretical predictions and compute the next-to-leading order corrections to photon +1, 2 jet production, using a clustering algorithm more closely matched to the experimental procedure.