Measurement of single top-quark production in association with a boson in collisions at with the ATLAS detector

The inclusive cross section for the production of a single top quark in association with a Formula Presented boson is measured using Formula Presented of proton-proton collision data collected with the ATLAS detector at Formula Presented. Events containing two charged leptons and at least one jet identified as originating from a Formula Presented-quark are selected. A multivariate discriminant is constructed to separate the Formula Presented signal from the Formula Presented background. The cross section is extracted using a profile likelihood fit to the signal and control regions and it is measured to be Formula Presented, in good agreement with the Standard Model prediction. The measured cross section is used to extract a value for the left-handed form factor at the Formula Presented vertex times the Cabibbo-Kobayashi-Maskawa matrix element Formula Presented of Formula Presented. © 2024 CERN, for the ATLAS Collaboration.