Measurement of -channel single-top-quark production in collisions at √ = 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_−4.1 ^+4.4(stat.)_−3.7 ^+4.4(syst.) pb and R_t=2.73_−0.82 ^+1.43(stat.)_−0.29 ^+1.01(syst.). The individual single-top-quark (tq) and single-top-antiquark (t¯q) production cross-sections are measured to be σ(tq)=19.8_−3.1 ^+3.9(stat.)_−2.2 ^+2.9(syst.) pb and σ(t¯q)=7.3_−2.1 ^+3.2(stat.)_−1.5 ^+2.8(syst.) pb. All measurements are in good agreement with the Standard Model predictions.