Search for single production of vector-like quarks decaying into <i>W</i>(<i>lν</i>)<i>b</i> in <i>pp</i> collisions at √<i>s</i> = 13 TeV with the ATLAS detector

A search for single production of a vector-like quark <i>Q</i>, which could be either a singlet <i>T</i>, with charge ²/₃, or a <i>Y</i> from a (<i>T</i>,<i>B</i>,<i>Y</i>) triplet, with charge -^4/₃, 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^-1 recorded with the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis targets <i>Q</i> →<i>Wb</i> decays where the <i>W </i>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 <i>Q</i> 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 <i>T</i>, the 95% confidence level limit on the coupling strength κ ranges between 0.22 and 0.52 for masses from 1150 to 2300 GeV. For the (<i>T</i>,<i>B</i>,<i>Y</i>) triplet, the limits on κ vary from 0.14 to 0.46 for masses from 1150 to 2600 GeV.