Full NLO QCD corrections to off-shell ttbb production

TL;DR

This paper presents the first complete NLO QCD calculation for off-shell ttbb production at the LHC, including all off-shell and interference effects, providing precise cross sections and distributions crucial for background estimation in Higgs analyses.

Contribution

It provides the first full NLO QCD computation for a 2→8 process with 6 external strongly-interacting partons, without approximations, including off-shell and interference effects.

Findings

Full NLO results differ from double-pole approximation by up to 10% in some regions.

Cross sections and distributions are computed with all off-shell and interference effects included.

The calculation enhances the precision of background modeling for ttH analyses.

Abstract

In this article, we report on the computation of the NLO QCD corrections to ${\rm p}{\rm p} \to \mu^-\bar\nu_{\mu}{\rm e}^+\nu_{\rm e}\bar{\rm b}{\rm b}\bar{\rm b}{\rm b}$ at the LHC, which is an irreducible background to ${\rm p}{\rm p}\to{\rm t}\bar{\rm t}{\rm H}\bigl(\to{\rm b}\bar{\rm b}\bigr)$. This is the first time that a full NLO computation for a $2\to8$ process with 6 external strongly-interacting partons is made public. No approximations are used, and all off-shell and interference effects are taken into account. Cross sections and differential distributions from the full computation are compared to results obtained by using a double-pole approximation for the top quarks. The difference between the full calculation and the one using the double-pole approximation is in general below 5\% but can reach 10\% in some regions of phase space.