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

TL;DR

This paper measures the single top-quark production cross section in the t-channel at 13 TeV with ATLAS, providing precise results and setting limits on EFT operators and CKM matrix elements.

Contribution

The paper presents the first precise measurement of the t-channel single top-quark cross section at 13 TeV and interprets the results in terms of EFT and CKM parameters.

Findings

Measured cross sections: 137 pb for top, 84 pb for antitop.

Combined cross section: 221 pb, ratio R_t: 1.636.

Set limits on EFT operator and CKM matrix elements.

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 $|V_{tb}|$.