Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector

TL;DR

This paper reports the first observation of single top quark production with an associated photon, providing insights into the top quark's electroweak interactions using extensive LHC data.

Contribution

It presents the first measurement of single top quark production with a photon, confirming the standard model prediction at the LHC.

Findings

Measured fiducial cross section: 688 ± 23 (stat.) +75/-71 (syst.) fb

Observed production consistent with the standard model prediction of 515 +36/-42 fb

Utilized 139 fb$^{-1}$ of 13 TeV proton-proton collision data

Abstract

This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb$^{-1}$ of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688 $\pm$ 23 (stat.) $^{+75}_{-71}$ (syst.) fb, to be compared with the standard model prediction of 515 $^{+36}_{-42}$ fb at next-to-leading order in QCD.