NLO QCD corrections to top anti-top bottom anti-bottom production at the LHC: 2. full hadronic results

TL;DR

This paper provides next-to-leading order QCD predictions for top-antitop bottom-antibottom production at the LHC, crucial for Higgs searches, with improved scale choices and detailed kinematic analyses.

Contribution

It introduces a new dynamical scale for more stable predictions and demonstrates high numerical stability in amplitude calculations.

Findings

Traditional scale underestimates background by a factor of two

New scale stabilizes perturbative predictions

Significant distribution distortions in boosted Higgs regime

Abstract

We present predictions for top anti-top bottom anti-bottom production at the LHC in next-to-leading order QCD. The precise description of this background process is a prerequisite to observe associated top anti-top Higgs production in the Higgs -> bottom anti-bottom decay channel and to directly measure the top-quark Yukawa coupling at the LHC. The leading-order cross section is extremely sensitive to scale variations. We observe that the traditional scale choice adopted in ATLAS simulations underestimates the top anti-top bottom anti-bottom background by a factor two and introduce a new dynamical scale that stabilizes the perturbative predictions. We study various kinematic distributions and observe that the corrections have little impact on their shapes if standard cuts are applied. In the regime of highly boosted Higgs bosons, which offers better perspectives to observe the top anti-top Higgs signal, we find significant distortions of the kinematic distributions. The one-loop amplitudes are computed using process-independent algebraic manipulations of Feynman diagrams and numerical tensor reduction. We find that this approach provides very high numerical stability and CPU efficiency.