NLO matching for t(t)over-barb(b)over-bar production with massive b-quarks

Theoretical uncertainties in the simulation of t (t) over barb (b) over bar production represent one of the main obstacles that still hamper the observation of Higgs-boson production in association with top-quark pairs in the H -> b (b) over bar channel. In this Letter we present a next-to-leading order (NLO) simulation of t (t) over barb (b) over bar production with massive b-quarks matched to the SHERPA parton shower. This allows one to extend NLO predictions to arbitrary t (t) over barb (b) over bar kinematics, including the case where one or both b-jets arise from collinear g -> b (b) over bar splittings. We find that this splitting mechanism plays an important role for the t (t) over barH(b (b) over bar) analysis. (C) 2014 The Authors. Published by Elsevier B.V.