Existence of Lambda-c D-bar and Lambda-c D-bar-star molecules

Determine whether the $\Lambda_c\bar{D}$ and $\Lambda_c\bar{D}^*$ systems form shallow bound states, given the sensitivity of their binding to the strength of the c3-meson-exchange interaction.

Background

The calculation predicts possible bbc\u0305D and bbc\u0305D* molecules with binding energies of approximately 500600 keV and radii near 5 fm. However, the authors state that the c3-exchange strength is not well constrained and that reducing the c3 coupling by about a factor of two eliminates the bound states. Their existence therefore remains unresolved and is proposed for clarification through future observations, particularly in the J/ψpJ/\psi p channel.

References

If $\Lambda_c\bar{D}{(*)}$ bound states exist indeed, they may have very narrow fall-apart width of a few tens of keV. To confirm the existence of the $\Lambda_c\bar{D}{(*)}$ states, the $J/\psi p$ channel is worth observing in future experiments.

— Hidden charm pentaquarks and the nature of $P_{c}$ states observed at LHCb  (2609.19749 - Liang et al., 17 Sep 2026) in Section 3, subsection 24\Lambda_c\bar{D}^{(*)}24 system