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.