A critical phenomenological study of inclusive photon production in hadronic collisions

We discuss fixed target and ISR inclusive photon production and attempt a c omparison between theory and experiments. The dependence of the theoretical predictions on the structure functions, and on the renormalization and fac torization scales is investigated. The main result of this study is that th e data cannot be simultaneously fitted with a single set of scales and stru cture functions. On the other hand, there is no need for an additional prim ordial k(T) to force the agreement between QCD predictions and experiments, with the possible exception of one data set. Since the data cover almost o verlapping kinematical ranges this raises the question of consistency among data sets. A comparative discussion of some possible sources of experiment al uncertainties is sketched.