# Top-quark pair-production and decay at high precision

## TL;DR

This paper provides a high-precision, fully-differential calculation of top-quark pair production and decay at the LHC, incorporating approximate and exact NNLO corrections, leading to improved agreement with experimental data.

## Contribution

It introduces the first implementation of exact NNLO corrections to top-quark decay processes in a differential Monte Carlo framework.

## Key findings

- NNLO corrections significantly affect cross section predictions
- Improved agreement with ATLAS and CMS measurements
- Enhanced accuracy in modeling top-quark events

## Abstract

We present a fully-differential and high-precision calculation of top-quark pair-production and decay at the LHC, providing predictions for observables constructed from top-quark leptonic and $b$-flavoured jet final states. The calculation is implemented in a parton-level Monte Carlo and includes an approximation to the next-to-next-to leading order (NNLO) corrections to the production and, for the first time, the exact NNLO corrections to the decay subprocesses. The corrections beyond NLO are sizeable, and including them is crucial for an accurate description of the cross section constrained by experimental phase-space restrictions. We compare our predictions to published ATLAS and CMS measurements at the LHC, finding improved agreement compared with lower orders in the perturbative expansion.