On the next-to-leading order QCD K-factor for t(t)over-barb(b)over-bar production at the TeVatron

Motivated by ongoing experimental analyses, we report on the calculation of next-to-leading order QCD corrections to the production of t (t) over bar pairs in association with two hard b-jets at the Fermilab TeVatron. Besides the total cross section and its scale dependence, a few differential distributions applicable for Higgs boson searches at the TeVaron are given. The QCD corrections with respect to leading order are negative and small. For our main setup they amount to 2%, and remain reasonably stable against changes of cuts. This proves that an integrated next-to-leading order K-factor does not necessarily need to be applied in the background estimation for the t (t) over barH -> t (t) over barb (b) over bar b signal process. The distributions show similarly small corrections. The shape of kinematic distributions is distorted at most by about 20% in some corners of the phase space. Even though it is not the main purpose of this paper, we also evaluated the forward-backward asymmetry of the top quark at next-to-leading order.