Search for pair-produced vector-like quarks coupling to light quarks in the lepton plus jets final state using 13 TeV $pp$ collisions with the ATLAS detector

TL;DR

This paper reports a search for pair-produced vector-like quarks decaying into a W boson and a light quark, using 13 TeV proton-proton collision data from the ATLAS detector, setting new mass exclusion limits.

Contribution

It presents the most stringent ATLAS limits to date on VLQ masses, utilizing improved analysis techniques and larger data set from Run 2.

Findings

Excluded VLQ masses below 1530 GeV at 95% CL.

Achieved an 840 GeV improvement over previous limits.

Analyzed 140 fb$^{-1}$ of 13 TeV collision data.

Abstract

A search is presented for the pair-production of heavy vector-like quarks (VLQs) that each decay into a $W$ boson and a light quark. This study focuses on events where one $W$ boson decays into leptons and the other into hadrons. The search analyzed 140 fb$^{-1}$ of $pp$ collision data with $\sqrt{s} = 13$ TeV, recorded by the ATLAS detector from 2015 to 2018 during Run 2 of the Large Hadron Collider. The final state is characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum, multiple small-radius jets, and a single large-radius jet identified as originating from the hadronic decay of a boosted $W$ boson. With higher center-of-mass energy and integrated luminosity than in the Run 1 search, and improved analysis tools, this analysis excludes VLQs ($Q$) with masses below 1530 GeV at 95% CL for the branching ratio ${{\cal B}(Q \to Wq)} = 1$, an improvement of 840 GeV on the previous ATLAS limit.