NLO QCD corrections to t tbar + jet production at hadron colliders

TL;DR

This paper delivers the first next-to-leading order QCD calculation for ttbar production in association with a hard jet at hadron colliders, focusing on both the cross section and the forward–backward charge asymmetry. The authors implement and cross-validate virtual and real corrections through two independent computational approaches, employing infrared subtraction and sophisticated tensor-integral techniques to ensure stability. They find that NLO corrections greatly reduce the LO scale uncertainty of the cross section and moderately adjust its magnitude, while the forward–backward asymmetry is substantially altered at NLO with a residual, small scale dependence. These results enhance the reliability of experimental analyses at the Tevatron and improve background estimates for LHC searches involving ttbar + jet processes.

Abstract

We report on the calculation of the next-to-leading order QCD corrections to the production of top--anti-top quark pairs in association with a hard jet at the Tevatron and at the LHC. We present results for the t tbar + jet cross section and the forward--backward charge asymmetry. The corrections stabilize the leading-order prediction for the cross section. The charge asymmetry receives large corrections.

Figures (4)

• Figure 1: A representative set of pentagon diagrams for hadronic $\mathrm{t}$t$\bar{\mathrm{t}$t$}{+}$jet production at NLO QCD.
• Figure 2: Scale dependence of the LO cross sections for $\mathrm{t}$t$\bar{\mathrm{t}$t$}{+}$jet production at the Tevatron (upper plot) and at the LHC (lower plot), where the renormalization and factorization scales are set equal to $\mu$. The individual contributions of the various partonic channels are shown also separately.
• Figure 3: Scale dependence of the LO and NLO cross sections for $\mathrm{t}$t$\bar{\mathrm{t}$t$}{+}$jet production at the Tevatron (upper plot) and at the LHC (lower plot), where the renormalization and factorization scales are set equal to $\mu$.
• Figure 4: Scale dependence of the LO and NLO forward--backward charge asymmetry of the top quark in $\mathrm{p}$p$\bar{\mathrm{p}$p$}\to\mathrm{t}$t$\bar{\mathrm{t}$t$}{+}$jet$+X$ at the Tevatron, where the renormalization and factorization scales are set equal to $\mu$.