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Inverse excitation hierarchy in doubly heavy tetraquarks within the diquark model

Maximilian Weber*

Daiki Suenaga†

Masayasu Harada‡

  • *Contact author: weber@hken.phys.nagoya-u.ac.jp
  • †Contact author: suenaga@hken.phys.nagoya-u.ac.jp
  • ‡Contact author: harada@hken.phys.nagoya-u.ac.jp
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Phys. Rev. D 114, 036012 – Published 10 August, 2026

DOI: https://doi.org/10.1103/lrtm-syh4

Abstract

We investigate the Tcc tetraquark, treating it as a bound state of a heavy diquark and a light antidiquark. Using the Silvestre-Brac potential and solving the Schrödinger equation via the Gaussian expansion method, we find that the excitation energy between the heavy diquark and light antidiquark is unexpectedly larger than that between the two light antiquarks within the antidiquark—contrary to the naive expectation where the former is smaller than the latter. We trace this inversion of the mass hierarchy to the centrifugal force acting on the light degree of freedom. Applying the same framework to other systems (Tbb,Λb,Λc) yields qualitatively identical behavior, demonstrating the robustness of the mechanism. These results provide new insights into diquark dynamics and the mass structure of exotic hadrons.

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Phys. Rev. D 114, 036012– Published 10 August, 2026
  • Received 17 March 2026
  • Accepted 22 June 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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