High-energy resummation of direct photon production at hadronic colliders

Direct photon production is an important process at hadron colliders, being relevant both for precision measurement of the gluon density, and as background to Higgs and other new physics searches. Here we explore the implications of recently derived results for high-energy resummation of direct photon production for the interpretation of measurements at the Tevatron and the LHC. The effects of resummation are compared to various sources of theoretical uncertainties like PDFs and scale variations. We show how the high-energy resummation procedure stabilizes the logarithmic enhancement of the cross section at high energy which is present at any fixed order in the perturbative expansion starting at NNLO. The effects of high-energy resummation are found to be negligible at Tevatron, while they enhance the cross section by a few percent for p(T) less than or similar to 10 GeV at the LHC. Our results imply that the discrepancy at small P-T between fixed order NLO and Tevatron data cannot be explained by unresummed high-energy contributions. (C) 2010 Elsevier B.V. All rights reserved.