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  • Open Access

Prospects for compact hexaquarks under the limitation imposed by quark confinement

Wen-Xuan Zhang1,2,3,*, Wen-Nian Liu4,5,†, and Duojie Jia2,6,‡

  • 1School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
  • 2Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Key Laboratory of Quantum Theory and Applications of MoE, Gansu Provincial Research Center for Basic Disciplines of Quantum Physics, Lanzhou University, Lanzhou 730000, China
  • 3Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, Lanzhou 730000, China
  • 4Institute of Theoretical Physics, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
  • 5Xinjiang Laboratory Phase Transitions and Microstructures in Condensed Matters, College of Physical Science and Technology, Yili Normal University, Yining 835000, China
  • 6General Education Center, Qinghai Institute of Technology, Xining 810000, China

  • *Contact author: zhangwx89@outlook.com
  • †Contact author: 1169994277@qq.com
  • ‡Contact author: djjia@qhit.edu.cn
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Phys. Rev. D 112, 114039 – Published 24 December, 2025

DOI: https://doi.org/10.1103/7ly3-j3fl

Abstract

The limitation of flavor constituents for compact multiquarks is crucial for understanding the strong interaction at the low energy scale. Utilizing the MIT bag model that incorporates perturbative interactions and confinement energy ECON, we derive a critical bag radius Rc=5.61  GeV−1 from the condition ECON<0 at zero temperature and zero baryon density, which aligns with the string-breaking distance of 1.2–1.4 fm. Applying this framework to 6-, 7-, and 8-quark systems, we find the bag radii R0 to be highly sensitive to relativistic effects from light quarks, leading to the exclusion of most heavy-light flavor configurations (e.g., n3c¯3, n3n¯c¯2) due to positive ECON and radii exceeding the critical radius. Color-spin wave functions are constructed using Young tableaux to evaluate interaction matrices and Okubo-Zweig-Iizuka-superallowed decays. Broad decay widths in fully heavy systems for Okubo-Zweig-Iizuka-superallowed modes could arise from wave function overlaps due to heavy flavor symmetry, suggesting possible narrow widths for nnbb¯b¯b¯ and nnnb¯b¯b¯ hexaquarks. This phenomenological approach provides insights into the limitations on multiquarks imposed by confinement. It recommends experimental searches at LHCb for these states.

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Phys. Rev. D 112, 114039– Published 24 December, 2025
  • Received 7 October 2025
  • Accepted 9 December 2025
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