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 +̄ 𝑡𝑞), and the ratio 𝑅 𝑡 between these two. They are measured to be 𝜎(𝑡𝑞 +̄ 𝑡𝑞) = 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 (̄𝑡𝑞) production cross-sections are measured to be 𝜎(𝑡𝑞) = 19.8+3.9−3.1 (stat.) +2.9−2.2 (syst.) pb and 𝜎(̄ 𝑡𝑞) = 7.3+3.2−2.1 (stat.) +2.8−1.5 (syst.) pb. All measurements are in good agreement with the Standard Model predictions.