Off-shell $t\bar{t}j$ production and top quark mass studies at the LHC

TL;DR

This paper presents a detailed NLO QCD calculation of off-shell $t\bar{t}j$ production at the LHC, analyzes off-shell effects versus NWA, and explores implications for precise top quark mass measurements.

Contribution

It provides the first full off-shell NLO QCD calculation of $pp \to e^+\nu_e\mu^-\bar{\nu}_\mu b \bar{b} j$ with leptonic decays, surpassing the Narrow Width Approximation.

Findings

Off-shell effects can significantly impact $t\bar{t}j$ observables.

Comparison shows differences between off-shell and NWA calculations.

Sensitivity analysis indicates potential for improved top mass extraction.

Abstract

Precision studies of the properties of the top quark represent a cornerstone of the LHC physics program. In this contribution we focus on the production of $t\bar{t}$ pairs in association with one hard jet and in particular on its connection with precision measurements of the top quark mass at the LHC. We report a summary of a full calculation of the process $pp \to e^+\nu_e\mu^-\bar{\nu}_\mu b \bar{b}j$ at NLO QCD accuracy, which describes $t\bar{t}j$ production with leptonic decays beyond the Narrow Width Approximation (NWA), and discuss the impact of the off-shell effects through comparisons with NWA. Finally we explore the sensitivity of $t\bar{t}j$ in the context of top-quark mass extraction with the template method, considering two benchmark observables as case studies.