Anatomy of inclusive $t\overline{t}W$ production at hadron colliders

TL;DR

This paper investigates higher-order QCD corrections to $t\overline{t}W$ production at the LHC, highlighting their potential to significantly increase predicted rates and the importance of full NNLO calculations for accurate modeling.

Contribution

It provides a detailed analysis of NLO and NNLO QCD corrections to $t\overline{t}W$ production, emphasizing the role of jet multiplicities and the need for complete NNLO results.

Findings

Higher-order corrections can increase $t\overline{t}W$ rates by 10-14%.

Multi-jet matching suggests a maximum increase of 10-12%.

Enhanced jet multiplicities align with experimental data.

Abstract

In LHC searches for new and rare phenomena the top-associated channel $pp \to t\overline{t}W^\pm +X$ is a challenging background that multilepton analyses must overcome. Motivated by sustained measurements of enhanced rates of same-sign and multi-lepton final states, we reexamine the importance of higher jet multiplicities in $pp \to t\overline{t}W^\pm +X$ that enter at $\mathcal{O}(\alpha_s^3\alpha)$ and $\mathcal{O}(\alpha_s^4\alpha)$, i.e., that contribute at NLO and NNLO in QCD in inclusive $t\overline{t}W^\pm$ production. Using fixed-order computations, we estimate that a mixture of real and virtual corrections at $\mathcal{O}(\alpha_s^4\alpha)$ in well-defined regions of phase space can arguably increase the total $t\overline{t}W^\pm$ rate at NLO by at least $10\%-14\%$. However, by using non-unitary NLO multi-jet matching, we estimate that these same corrections are at most $10\%-12\%$, and at the same time exhibit the enhanced jet multiplicities that are slightly favored by data. This seeming incongruity suggests a need for the full NNLO result. We comment on implications for the $t\overline{t}Z$ process.