Compositeness of the strange, charm and beauty odd parity $\Lambda$ states

TL;DR

This study investigates how the compositeness of the lowest-lying odd parity hyperon states varies with quark mass across strange, charm, and beauty sectors, using a unitarized meson-baryon model with heavy-quark symmetry.

Contribution

It introduces a unified approach combining SU(6) extension and heavy-quark spin symmetry to analyze hyperon states across different flavor sectors.

Findings

Bound states and narrow resonances are well described as molecular meson-baryon states.

Wide resonances show smaller compositeness, indicating the need for additional interaction mechanisms.

The model successfully reproduces specific $ ext{Lambda}$ states across sectors.

Abstract

We study the dependence on the quark mass of the compositeness of the lowest-lying odd parity hyperon states. Thus, we pay attention to $\Lambda-$like states in the strange, charm and beauty, sectors which are dynamically generated using a unitarized meson-baryon model. In the strange sector we use an SU(6) extension of the Weinberg-Tomozawa meson-baryon interaction, and we further implement the heavy-quark spin symmetry to construct the meson-baryon interaction when charmed or beauty hadrons are involved. In the three examined flavor sectors, we obtain two $J^P=1/2^-$ and one $J^P=3/2^-$ $\Lambda$ states. We find that the $\Lambda$ states which are bound states (the three $\Lambda_b$) or narrow resonances (one $\Lambda(1405)$ and one $\Lambda_c(2595)$) are well described as molecular states composed of $s$-wave meson-baryon pairs. The $\frac{1}{2}^-$ wide $\Lambda(1405)$ and $\Lambda_c(2595)$ as well as the $\frac{3}{2}^-$ $\Lambda(1520)$ and $\Lambda_c(2625)$ states display smaller compositeness and so they would require new mechanisms, such as $d$-wave interactions.