Measurement of the $t$-channel single top-quark production cross section at $\sqrt{s}=13$ TeV with the ATLAS detector and interpretations of the measurement

The t t -channel is the dominant production channel for single top-quarks at the LHC. The total cross section of this process is measured by ATLAS in proton-proton collisions at a center-of-mass energy \sqrt{s}=13 s = 13 TeV. The production cross sections for single top-quarks and single top-antiquarks are measured to be \sigma_{tq}=\text{137}^{+8}_{-8}\, σ t q = 137 − 8 + 8 pb and \sigma_{\bar{t}q}=\text{84}^{+6}_{-5}\, σ t ‾ q = 84 − 5 + 6 pb. For the combined cross section and the ratio of the cross sections R_t R t , \sigma_{tq+\bar{t}q}=\text{221}^{+13}_{-13}\, σ t q + t ‾ q = 221 − 13 + 13 pb and R_t=\text{1.636}^{+0\text{.}036}_{-0\text{.}034} R t = 1.636 − 0 . 034 + 0 . 036 are obtained. As interpretations of the measurement, limits are set on the EFT operator O_{Qq}^{3,1} O Q q 3 , 1 and on the CKM matrix elements |V_{td}| | V t