A full next-to-leading order study of direct photon pair production in hadronic collisions

We discuss the production of photon pairs in hadronic collisions, from fixed target to LHC energies. The study which follows is based on a QCD calculation at full next-to-leading order accuracy, including single and double fragmentation contributions, and implemented in the form of a general purpose computer program of partonic event generator type. To illustrate the possibilities of this code, we present a comparison with observables measured by the WA70 and DO collaborations, and some predictions for the irreducible background to the search of Higgs bosons at LHC in the channel h --> gamma gamma. We also discuss theoretical scale uncertainties for these predictions, and examine several infrared sensitive situations which deserve further study.