Investigating the Molecular Nature of $\Lambda_b(6146)$ and $\Lambda_b(6152)$ via Strong Decays and Predicting Their Heavy-Quark Symmetry Partners

Abstract

Heavy quark symmetry can help us identify the internal structure of hadrons and predict new particles. In this study, we examine the strong decay modes of the observed $\Lambda_b^0(6146)$ and $\Lambda_b^0(6152)$, assuming these two states are molecular states primarily composed of $\bar{B}^{*}N$ component. The partial decay widths of the $\bar{B}^{*}N$ molecular state into the $\pi\Sigma_b$ and $\pi\Sigma_b^{*}$ final states through hadronic loops are calculated using effective Lagrangians. Our results, when compared with LHCb observations, support the interpretation of $\Lambda_b^0(6146)$ as a molecule primarily composed of $\bar{B}^{*}N$ components. However, the decay width of $\Lambda_b^0(6152)$ cannot be accurately reproduced within the molecular state framework. Based on the above results and heavy quark symmetry, we predict the existence of $\bar{B}^{*}N$ molecular states with $J^p=5/2^{+}$, which are the heavy quark spin symmetry partners of $\Lambda_b(6146)$, with masses in the range of 6195-6200 MeV. And the main decay is $\pi\Sigma_b^{*}$ channel. Moreover, there must existence of a $D^{*}N$ molecule with $J^p=3/2^{+}$, possible corresponding to the experimentally observed $\Lambda_c(2860)^{+}$. If $\Lambda_c(2880)^{+}$ is indeed the heavy quark flavor symmetry partner of $\Lambda_b(6152)$, it would exhibit a conventional three-quark structure. Therefore, we also propose the search for a $D^{*}N$ molecule with a spin-parity of $J^p=5/2^{+}$, which would be the heavy-quark spin partner state of $\Lambda_c(2860)^{+}$. It should be noted that these baryons may be mixed states, containing both molecular and three-quark components. These results can aid experiments in exploring the internal structure of these baryons.