Higher order corrections to Higgs production at hadron colliders and their phenomenological consequences

Abstract

Next-to-leading order corrections in perturbative QCD are computed with full mass dependence for Higgs production through gluon fusion, the main production mechanism at hadron colliders. Analytic results for the virtual amplitudes are obtained for fermionic and scalar particles and provide the first independent check of known results. Together with real radiation corrections the virtual corrections are combined into a suitable expression for numerical evaluation using the FKS subtraction method. The results are incorporated in a new fully differential Monte-Carlo program. Phenomenological important decay channels, h → γγ, h → WW → νν and h → ZZ → ′′ are implemented and arbitrary selection cuts can be applied. It is the first code for Higgs production at next-to-leading order taking into account the full mass dependence of the matrix elements and thus, it will be an useful tool for phenomenological studies at hadron colliders. The mass effects on distributions are studied in detail for the production of a Standard Model Higgs. In agreement with similar studies, we find that mass effects are mild for most distributions but sizable for high transverse momentum tails. Our code is then used to correct an existing Monte-Carlo program at next-to-next-toleading order employing the approximation of an infinitely heavy quark mass. Recently computed electroweak virtual and real corrections are integrated as well and most up to date predictions for Higgs production obtained. The most dominant decay channels are studied and the analysis of experimentally relevant distributions confirms the excellent approximation of the calculation in the effective theory. First studies at next-to-leading order of light and heavy CP even Higgs production in the Minimal Supersymmetric Standard Model (MSSM) retaining the full mass dependence are performed, using numerical results for more complicated virtual corrections involving many mass scales. We find that in certain regions of the MSSM parameter space these mass effects alter the production rate significantly.