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 events election 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_−1.5(syst.) pb. All measurements are in good agreement with the Standard Model predictions.