Renormalization-group improved fully differential cross sections for top pair production

TL;DR

This paper enhances top-pair production predictions by incorporating approximate NNLO corrections with decay processes into a fully differential Monte Carlo framework, improving accuracy and robustness of theoretical predictions.

Contribution

It introduces a fully differential Monte Carlo implementation of approximate NNLO corrections including top decays, enabling detailed IR-safe observable analysis.

Findings

Renormalization-group framework provides robust predictions.

Approximate NNLO corrections reduce theoretical uncertainties.

Differential approach allows comparison of different kinematic schemes.

Abstract

We extend approximate next-to-next-to-leading order results for top-pair production to include the semi-leptonic decays of top quarks in the narrow-width approximation. The new hard-scattering kernels are implemented in a fully differential parton-level Monte Carlo that allows for the study of any IR-safe observable constructed from the momenta of the decay products of the top. Our best predictions are given by approximate NNLO corrections in the production matched to a fixed order calculation with NLO corrections in both the production and decay subprocesses. Being fully differential enables us to make comparisons between approximate results derived via different (PIM and 1PI) kinematics for arbitrary distributions. These comparisons reveal that the renormalization-group framework, from which the approximate results are derived, is rather robust in the sense that applying a realistic error estimate allows us to obtain a reliable prediction with a reduced theoretical error for generic observables and analysis cuts.