Large perturbative corrections in the soft-gluon limit

Corrections to certain hadronic reactions involving photons are studied at O(α/sub s//sup ts2/) in the soft-gluon limit; in this limit we carefully preserve the analytic structure of amplitudes in the small-momenta integration regions. For the production of real or virtual photons at large p/sub T/ via the quark-gluon channel the result is a rather larger correction to the Born term. The phenomenological status of p+p→γ+X at large p/sub T/ is discussed, and the large correction is shown to significantly improve agreement with data. The same technique is applied to study O(α/sub s//sup ts2/) corrections to e+e-→3 jets; here it reproduces the π2 terms that are the dominant part of the known correction to this process. Some remarks on other reactions, including hadronic lepton-pair and single-lepton production are made and the nature of the problem of nonleading large corrections is discussed