Modelling uncertainties of $t\overline{t}W$ in multi-lepton channel

TL;DR

This paper compares fixed order and parton shower predictions for the $t\overline{t}W$ process in multi-lepton channels at the LHC, proposing a new method to include off-shell effects in simulations.

Contribution

It introduces a novel prescription to incorporate approximate full off-shell effects into NLO QCD predictions with parton shower matching.

Findings

Comparison of fixed order and shower-matched predictions at NLO QCD.

A new prescription for including off-shell effects in simulations.

Enhanced accuracy in modeling $t\overline{t}W$ production at the LHC.

Abstract

We compare fixed order and parton shower matched predictions for the process ${pp\rightarrow \ell^+\nu_{\ell} \ell^-\bar{\nu}_{\ell} \ell^{\pm}{\nu}_{\ell} b\bar{b}+X}$ at NLO in QCD, including the orders $\mathcal{O}(\alpha_s^3\alpha^6)$ and $\mathcal{O}(\alpha_s\alpha^8)$. The comparison is performed at the integrated and differential fiducial level at the LHC with $\sqrt{s}=13$ TeV. In the absence of parton shower matching procedure that includes the full off-shell effects for this process at NLO in QCD, we propose a new prescription. It enables the inclusion of approximate full off-shell effects to currently available parton shower matched predictions at NLO in QCD.