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

Abstract: The $t$-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 $\sqrt{s}=13$ TeV. The production cross sections for single top-quarks and single top-antiquarks are measured to be $\sigma_{tq}=\text{137}^{+8}_{-8}$ pb and $\sigma_{\bar{t}q}=\text{84}^{+6}_{-5}$ pb. For the combined cross section and the ratio of the cross sections $R_t$, $\sigma_{tq+\bar{t}q}=\text{221}^{+13}_{-13}$ pb and $R_t=\text{1.636}^{+0\text{.}036}_{-0\text{.}034}$ are obtained. As interpretations of the measurement, limits are set on the EFT operator $O_{Qq}^{3,1}$ and on the CKM matrix elements $|V_{td}|$, $|V_{ts}|$ and $|V_{tb}|$.