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HL-LHC sensitivity to an ultraheavy Suu diquark in the uχ channel

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

  • *Contact author: calin.alexa@cern.ch
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Phys. Rev. D 114, 055051 – Published 29 September, 2026

DOI: https://doi.org/10.1103/8vcn-frj7

Abstract

We study the HL-LHC sensitivity to an ultraheavy diquark Suu produced in up-quark fusion and decaying through a vectorlike quark (VLQ) χ as Suu→uχ, with χ→Wb,Zt,h0t. For fully hadronic decays of the W, Z and top quark, these modes give rise to multijet final states with different jet multiplicities. Within the same model framework used previously for the Suu→χχ six-jet channel, we consider Suu masses in the multi-TeV range and VLQ masses of the order of a few TeV, and simulate proton–proton collisions at s=13.6  TeV with integrated luminosities up to the HL-LHC target. The analysis employs a machine learning-based discriminant adapted from the six-jet study to the Suu→uχ topology, and is used to derive the corresponding discovery reaches and exclusion limits. We find that the uχ channel provides a complementary signature for ultraheavy diquark searches, especially in regions where the branching ratio B(Suu→uχ) is sizable, thereby broadening the sensitivity program for Suu production at the HL-LHC.

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Phys. Rev. D 114, 055051– Published 29 September, 2026
  • Received 22 January 2026
  • Accepted 13 July 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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