Probing $t$-channel single top-quark and antiquark production via differential cross-section measurements at $\sqrt{s}=$\SI{13}{\TeV} with the ATLAS detector

TL;DR

This paper measures the differential cross-sections of single top quark and antiquark production via the t-channel at 13 TeV using ATLAS data, including the first differential ratio of these processes, and compares results to theoretical models.

Contribution

It provides the first differential ratio measurement of t-channel single top and antiquark production and constrains an EFT Wilson coefficient using these data.

Findings

Differential cross-sections measured as functions of top quark transverse momentum and rapidity.

First measurement of the differential ratio of t-channel top quark to antiquark production.

Results compared with various theoretical predictions and used to constrain EFT parameters.

Abstract

The differential production cross-sections of single top quarks and top antiquarks produced via the $t$-channel process are measured in proton-proton collisions at $\sqrt{s}=13$TeV at the LHC with the full Run~2 ATLAS dataset corresponding to an integrated luminosity of \SI{140}{\femto\barn^{-1}}. The cross-sections are measured as a function of the transverse momentum and absolute rapidity of the top quark ($tq$) and top antiquark ($\bar{t}q$) at parton level. In addition, for the first time, the differential ratio of the $tq$ to $\bar{t}q$ cross-sections is presented. The results are compared to theoretical predictions from fixed-order calculations, various event generators, and different PDF sets. An interpretation in the framework of an effective field theory (EFT) is performed to constrain the Wilson coefficient $C^{3,1}_{Qq}$ of the four-fermion operator.