Systematic investigation of the spectroscopy and decay behaviors of doubly-charmed pentaquarks

Abstract Building upon the discoveries of the $$\Xi ^{++}_{cc}(3621)$$ Ξ cc + + ( 3621 ) and $$T^{+}_{cc}(3875),$$ T cc + ( 3875 ) , we undertake a comprehensive investigation into the mass spectra, internal structures, and decay properties of doubly-charmed pentaquarks. By treating the two light quarks as a tightly bound diquark, the five-body system reduces to a four-body heavy quark-heavy quark–diquark–antiquark configuration. Within the constituent quark model framework, we calculate their mass spectra in the range of 4.7–5.4 GeV and corresponding internal mass contributions via the Gaussian expansion method. The root-mean-square radii, typically between 1.1–1.6 fm, indicate compact spatial structures. Furthermore, we also calculate the rearrangement decay widths via the quark-interchange model, finding that all states are unstable and decay into a singly-charmed baryon and a singly-charmed meson. Several narrow resonances have been identified, some of which have a total width even below 10 MeV. We hope that our study could provide valuable guidance for future theoretical investigations and experimental searches targeting doubly-charmed pentaquarks.