Search for single production of vector-like quarks decaying into $\textit{W}$($\textit{ℓν}$)$\textit{b}$ in $\textit{pp}$ collisions at TeV with the ATLAS detector

A search for single production of a vector-like quark $\textit{Q}$, which could be either a singlet $\textit{T}$, with charge , or a $\textit{Y}$ from a ($\textit{T}$, $\textit{B}$, $\textit{Y}$) triplet, with charge , is performed using data from proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to the full integrated luminosity of 140 fb recorded with the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis targets $\textit{Q}$ → $\textit{Wb}$ decays where the $\textit{W}$ boson decays leptonically. The data are found to be consistent with the expected Standard Model background, so upper limits are set on the cross-section times branching ratio, and on the coupling of the $\textit{Q}$ to the Standard Model sector for these two benchmark models. Effects of interference with the Standard Model background are taken into account. For the singlet $\textit{T}$, the 95% confidence level limit on the coupling strength $\textit{κ}$ ranges between 0.22 and 0.52 for masses from 1150 to 2300 GeV. For the ($\textit{T}$, $\textit{B}$, $\textit{Y}$) triplet, the limits on $\textit{κ}$ vary from 0.14 to 0.46 for masses from 1150 to 2600 GeV.