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  • Open Access

Predictions for the scalar partner of the LHC tetraquark X(6600)

Muhammad Naeem Anwar* and Timothy J. Burns†

  • Centre for Quantum Fields and Gravity, Department of Physics, Swansea University, Singleton Park, Swansea, SA2 8PP, United Kingdom

  • *Contact author: m.n.anwar@swansea.ac.uk
  • †Contact author: t.burns@swansea.ac.uk
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Phys. Rev. D 114, 074040 – Published 16 October, 2026

DOI: https://doi.org/10.1103/1p7c-3prv

Abstract

We consider how the recent CMS measurements of the masses and quantum numbers of X(6600), X(6900) and X(7100) can help to reveal the internal structure of these apparent ccc¯c¯ tetraquarks. The measured JPC=2++ quantum numbers of X(6600) are consistent with our previous prediction, and imply the inevitable existence of a lighter 0++ partner X(6400) which also decays to J/ψJ/ψ. There are strong indications for this scalar partner in the recent CMS data fits, which include a Breit-Wigner peak with mass around 6400 MeV. We provide predictions for the masses and decay properties of the scalar and other partner states, which are key experimental tests to discriminate between quark and diquark models. Dedicated experimental scrutiny of this mass region is therefore required, to establish an S-wave multiplet of ccc¯c¯ states (the first of its kind for tetraquarks), leading to a breakthrough in exotic hadron research and our understanding of heavy quark exotics.

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Phys. Rev. D 114, 074040– Published 16 October, 2026
  • Received 7 May 2026
  • Accepted 26 August 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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