Top-quark processes at NLO in production and decay

TL;DR

This paper presents an implementation of top-quark production and decay processes at NLO in a Monte Carlo program, enabling detailed simulations with spin correlations and mass effects for LHC and Tevatron analyses.

Contribution

It introduces a method to factorize top production and decay amplitudes at NLO, including spin correlations and b-quark mass effects, within the MCFM program.

Findings

Accurate NLO predictions for top-quark kinematic distributions at LHC.

Analysis of top quark forward-backward asymmetry at Tevatron.

Retention of spin correlations and mass effects in simulations.

Abstract

We describe the implementation of top production and decay processes in the parton-level Monte Carlo program MCFM. By treating the top quark as being on-shell, we can factorize the amplitudes for top-pair production, s-channel single-top production, and t-channel single-top production into the product of an amplitude for production and an amplitude for decay. In this way we can retain all spin correlations. Both the production and the decay amplitudes are calculated consistently at next-to-leading order in alpha_s. The full dependence on the b-quark mass is also kept. Phenomenological results are presented for various kinematic distributions at the LHC and for the top quark forward-backward asymmetry at the Tevatron.