Measurement of single top-quark production in the s-channel in proton–proton collisions at s = 13 TeV with the ATLAS detector.

A measurement of single top-quark production in the s-channel is performed in proton–proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb−1. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two b-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is σ = 8.2 − 2.9 + 3.5 pb, consistent with the Standard Model prediction of σ SM = 10.32 − 0.36 + 0.40 pb. [ABSTRACT FROM AUTHOR]