Bound-state Effects on Top Quark Production at Hadron Colliders

TL;DR

This paper investigates how bound-state effects influence top-antitop production near threshold at hadron colliders, especially the LHC, showing significant enhancements and distortions in distributions due to resonance formations.

Contribution

It provides the first detailed predictions of tar{t} invariant-mass distributions incorporating bound-state effects and NLO initial-state radiation at hadron colliders.

Findings

Bound-state effects cause a peak a few GeV below threshold.

Enhancement of tar{t} production over naive predictions.

Significant deformation of top-quark kinematic distributions.

Abstract

We study bound-state effects on the t\bar{t} 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\bar{t} resonances in the J=0 color-singlet channel of gg \to t\bar{t} and the large width of the top quark, the t\bar{t} invariant-mass distribution peaks at a few GeV below the t\bar{t} threshold, and it is significantly enhanced over the naive NLO prediction until several GeV above the threshold. We present predictions of the t\bar{t} invariant-mass distribution which incorporate both the bound-state 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.