Measurement of Single Top-Quark Production in Association With a W Boson in <i>pp</I> Collisions at √<i>s</I>=13 Tev With the Atlas Detector

Abstract

The inclusive cross section for the production of a single top quark in association with a W boson is measured using 140 fb(-1) of proton-proton collision data collected with the ATLAS detector at root s = 13 TeV. Events containing two charged leptons and at least one jet identified as originating from a b-quark are selected. A multivariate discriminant is constructed to separate the tW signal from the t (t) over bar background. The cross section is extracted using a profile likelihood fit to the signal and control regions and it is measured to be sigma(tW) = 75(-14)(+15) pb, 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 Wtb vertex times the CabibboKobayashi-Maskawa matrix element vertical bar f(LV)V(tb)vertical bar of 0.97 +/- 0.10.