The qT spectrum of the Higgs boson at the LHC in QCD perturbation theory

We consider the transverse-momentum (q(T)) distribution of Higgs bosons produced at hadron colliders. We use a formalism that uniformly treats both the small-q(T) and large-q(T) regions in QCD perturbation theory. At small q(T) (q(T) much less than M-H, M-H being the mass of the Higgs boson), we implement an all-order resummation of logarithmically-enhanced contributions up to next-to-next-to-leading logarithmic accuracy. At large q(T) (q(T) greater than or similar to MH), we use fixed-order perturbation theory up to next-to-leading order. The resummed and fixed-order approaches are consistently matched by avoiding double-counting in the intermediate-q(T) region. In this region, the introduction of unjustified higher-order terms is avoided by imposing unitarity constraints, so that the integral of the q(T) spectrum exactly reproduces the perturbative result for the total cross section up to next-to-next-to-leading order. Numerical results at the LHC are presented. These show that the main features of the q(T) distribution are quite stable with respect to perturbative QCD uncertainties. (C) 2003 Elsevier Science B.V. All rights reserved.