Measurement of t-channel single-top-quark production in pp collisions at √s = 5.02 TeV with the ATLAS detector

The observation of the electroweak production of single-top-quarks is made using 255 pb^-1 of proton-proton collision data recorded at √s = 5.02 TeV with the ATLAS detector at the Large Hadron Collider. An event selection is used to identify single-top-quark candidates arising from t-channel production with the top quark decaying semi-leptonically. Events passing the selection are then used to measure the inclusive cross-section for the combined production of single-top-quarks and antiquarks, σ (tq + t^-q), and the ratio R_t between these two. They are measured to be σ (tq + t^-q) = 27.1^+4.4_-4.1 (stat.) ^+4.4_-3.7 (syst.) pb and R_t = 2.73^+1.43_-0.82 (stat.) ^+1.01_-0.29 (syst.). The individual single-top-quark (tq) and single-top-antiquark (t^-q) production cross-sections are measured to be σ (tq) = 19.8^+3.9-_3.1 (stat.)^+2.9_-2.2 (syst.) pb and σ (t^-q) = 7.3^+3.2_-2.1 (stat.) ^+2.8_-2.1 (syst.) pb. All measurements are in good agreement with the Standard Model predictions.