Search for resonant production of dark quarks in the dijet final state with the ATLAS detector

Abstract

<p>This paper presents a search for a new <em>Z</em>′ resonance decaying into a pair of dark quarks which hadronise into dark hadrons before promptly decaying back as Standard Model particles. This analysis is based on proton-proton collision data recorded at 𝑠 = 13 TeV with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb^{<em>−</em>1}. After selecting events containing large-radius jets with high track multiplicity, the invariant mass distribution of the two highest-transverse-momentum jets is scanned to look for an excess above a data-driven estimate of the Standard Model multijet background. No significant excess of events is observed and the results are thus used to set 95% confidence-level upper limits on the production cross-section times branching ratio of the <em>Z</em>′ to dark quarks as a function of the <em>Z</em>′ mass for various dark-quark scenarios.<br></p>