Top quark pair + jet production at next-to-leading order: NLO QCD corrections to gg -> t tbar g

TL;DR

This paper presents a full next-to-leading order QCD calculation for the partonic process $gg\to t\bar{t} g$, addressing both virtual and real corrections. It details the treatment of complex pentagon (5-point) loop integrals with two independent reduction approaches to ensure numerical stability, and applies the dipole subtraction method to isolate and cancel infrared divergences in real-emission contributions. The authors implement the major components in a numerical framework and perform cross-checks, including agreement between different computation methods and finite results after renormalization and subtraction. The work lays the groundwork for precise predictions of $t\bar{t}+\text{jet}$ production, which is a key background for Higgs searches and a laboratory for precision top-quark measurements at hadron colliders.

Abstract

The reaction pp/pbar p -> t tbar jet+X is an important background process for Higgs boson searches in the mass range below 200 GeV. Apart from that it is also an ideal laboratory for precision measurements in the top quark sector. Both applications require a solid theoretical prediction, which can be achieved only through a full next-to-leading order (NLO) calculation. In this work we describe the NLO computation of the subprocess gg -> t tbar g.

Figures (3)

• Figure 1: Sample Feynman diagrams contributing to the virtual corrections.
• Figure 2: Sample Feynman diagram contributing to the real corrections.
• Figure 3: Result for the virtual corrections for the subprocess $gg\to t\bar{t} g$ as defined by the second term in Eq. (\ref{['eq:SubtractionMethod']}) ($k_\perp>$ 20 GeV).