Bound-state effects on top quark production at hadron colliders

We study bound-state effects on the t (t) over bar production cross section in the threshold region at hadron colliders. The bound-state effects are important particularly at the LHC where the gluon fusion is the dominant subprocess. Due to the formation of t (t) over bar resonances in the J = 0 color-singlet channel of gg -> t (t) over bar and the large width of the top quark, the t (t) over bar invariant-mass distribution peaks at a few GeV below the t (t) over bar threshold, and it is significantly enhanced over the naive NLO prediction until several GeV above the threshold. We present predictions of the t (t) over bar invariant-mass distribution which incorporate both the boundstate effects and initial-state radiations up to NLO. The bound-state effects would lead to a substantial deformation of top-quark kinematical distributions in the threshold region. (c) 2008 Elsevier B.V. All rights reserved.