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Observability of an ultraheavy diquark decaying into vectorlike quarks at the LHC

Daniel C. Costache1,2, Calin Alexa1,*, Anca M. Dinu1,2, Ioan M. Dinu1, Ioana Duminica1,2, Matei S. Filip1,2, and Gabriel C. Majeri2

  • *Contact author: calin.alexa@cern.ch
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Phys. Rev. D 113, 115056 – Published 22 June, 2026

DOI: https://doi.org/10.1103/qxhl-4pqz

Abstract

We present a comprehensive analysis of the discovery reach and exclusion limits for an ultraheavy diquark scalar (7–9.5 TeV) decaying into a pair of vectorlike quarks (1.5–2 TeV) at the HL-LHC. Building on an improved signal selection efficiency achieved using machine learning techniques, we extend our previous six-jet final-state study by providing a complete likelihood-based statistical treatment of this search topology. The analysis incorporates theoretical and systematic uncertainties through nuisance parameters within the likelihood framework, enabling a consistent statistical interpretation. The mass regions of interest were determined through scans of the local p-values, CLs, and the upper limits on the model-dependent signal strength μ. The results indicate a promising sensitivity to ultraheavy diquark scalars within the explored mass range, suggesting that the HL-LHC could either discover or set stringent exclusion limits on such particles.

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Outline

Information

Phys. Rev. D 113, 115056– Published 22 June, 2026
  • Received 10 November 2025
  • Accepted 14 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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