Higher-order QCD corrections to top-quark pair production in association with a jet

In this paper, collaborators and I present the first high-precision theoretical predictions for the production of a top-quark pair alongside a jet of other particles at the Large Hadron Collider (LHC). The top quark is the heaviest known elementary particle, and its mass is a critical parameter for testing the consistency and phenomenology of the Standard Model of Particle Physics. This “top-quark pair plus jet” interaction is a cornerstone of modern physics because approximately 50% of all top-quark events at the LHC occur with an associated jet, making it a vital signal for studying top-quark properties and a significant background process when searching for new physics beyond our current understanding.

While basic “Next-to-Leading Order” (NLO) predictions were available for some time, the incredible accuracy of modern LHC data now requires “Next-to-Next-to-Leading Order” (NNLO) calculations to keep theoretical uncertainties in line with experimental results. Achieving this level of precision represents a massive computational challenge due to “two-loop” amplitudes, which we computed in another publication and use them here for the first time in a phenomenological study.

The results show that these second-order QCD corrections are essential for achieving a theoretical precision of under 10%.

Higher-order QCD corrections to top-quark pair production in association with a jet

Authors: Simon Badger, Matteo Becchetti, Colomba Brancaccio, Michał Czakon, Heribertus Bayu Hartanto, Rene Poncelet, Simone Zoia

Abstract: The production of a top-quark pair, the heaviest known elementary particle, in association with a light jet is a key process for studying the properties of the Standard Model of Particle Physics. Due to its significance as a signal process with considerable sensitivity to the top-quark mass and as a background process for new physics searches, it is crucial to predict differential cross sections with high precision. In this article, we present, for the first time, predictions for various kinematical observables at next-to-next-to-leading order in Quantum Chromodynamics. The perturbative behavior is analyzed, and uncertainties arising from missing higher-order contributions are substantially reduced. The necessary two-loop amplitudes have been evaluated in the leading-color approximation, and we provide estimates for the impact of the missing contributions.

Article on arxiv.org