2025 Articles

Search for single-production of vector-like quarks decaying into 𝑊𝑏 in the fully hadronic final state in 𝑝𝑝 collisions at √𝒔 = 13 TeV with the ATLAS detector

Aad, G.; Aakvaag, E.; Abbott, B.; Abdelhameed, S.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboelela, M.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Ackermann, A.; Adam Bourdarios, C.; Adamczyk, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Adye, T.; Affolder, A. A.; Afik, Y.; Agaras, M. N.; Agarwala, J.; Aggarwal, A.; Agheorghiesei, C.; Ahmadov, F.; Ahmed, W. S.; Ahuja, S.; Ai, X.; Aielli, G.; Aikot, A.; Ait Tamlihat, M.; Aitbenchikh, B.; Akbiyik, M.; Åkesson, T. P. A.; Akimov, A. V.; Akiyama, D.; Akolkar, N. N.; Al Khoury, Konie; Angerami, Aaron; Busch, Elena Laura; Cole, Brian A.

A search for 𝑇 and 𝑌 vector-like quarks produced in proton-proton collisions at a centre-of-mass energy of 13 TeV and decaying into 𝑊𝑏 in the fully hadronic final state is presented. The search uses 139 fb⁻¹ of data collected by the ATLAS detector at the LHC from 2015 to 2018. The final state is characterised by a hadronically decaying 𝑊 boson with large Lorentz boost and a 𝑏-tagged jet, which are used to reconstruct the invariant mass of the vector-like quark candidate.

The main background is QCD multijet production, which is estimated using a data-driven method. Upon finding no significant excess in data, mass limits at 95% confidence level are obtained as a function of the global coupling parameter, 𝜅. The observed lower limits on the masses of 𝑌 quarks with 𝜅 = 0.5 and 𝜅 = 0.7 are 2.0 TeV and 2.4 TeV, respectively. For 𝑇 quarks, the observed mass limits are 1.4 TeV for 𝜅 = 0.5 and 1.9 TeV for 𝜅 = 0.7.