NLO QCD corrections to top anti-top bottom anti-bottom production at the LHC: 1. quark-antiquark annihilation

TL;DR

This paper calculates the next-to-leading-order QCD corrections to the quark-antiquark annihilation subprocess in top anti-top bottom anti-bottom production at the LHC, aiding background understanding for Higgs searches.

Contribution

It provides the first NLO QCD correction calculation for the quark-antiquark initiated subprocess in top anti-top bottom anti-bottom production at the LHC.

Findings

NLO QCD corrections calculated for quark-antiquark annihilation subprocess.

Analysis of rational terms from UV and IR singularities in dimensional regularization.

Clarification that IR-origin rational terms cancel in Feynman gauge for arbitrary processes.

Abstract

The process pp -> top anti-top bottom anti-bottom + X represents a very important background reaction to searches at the LHC, in particular to top anti-top H production where the Higgs boson decays into a bottom anti-bottom pair. A successful analysis of top anti-top H at the LHC requires the knowledge of direct top anti-top bottom anti-bottom production at next-to-leading order in QCD. We take the first step in this direction upon calculating the next-to-leading-order QCD corrections to the subprocess initiated by quark anti-quark annihilation. We devote an appendix to the general issue of rational terms resulting from ultraviolet or infrared (soft or collinear) singularities within dimensional regularization. There we show that, for arbitrary processes, in the Feynman gauge, rational terms of infrared origin cancel in truncated one-loop diagrams and result only from trivial self-energy corrections.