Eur. Phys. J. A (2023) 59: 262
https://doi.org/10.1140/epja/s10050-023-01167-5

Regular Article - Theoretical Physics

Molecular states from ${\overline{B}}^{(\ast )}N$ interactions

¹ School of Physical Science and Technology, Southwest Jiaotong University, 610031, Chengdu, China
² College of Physics and Electronic Engineering, Chongqing Normal University, 401331, Chongqing, China
³ Asia Pacific Center for Theoretical Physics, Pohang University of Science and Technology, 37673, Pohang, Gyeongsangbuk-do, South Korea
⁴ School of Physics and Technology, Nanjing Normal University, 210097, Nanjing, China

^d yin.huang@apctp.org

Received: 14 April 2023
Accepted: 14 October 2023
Published online: 9 November 2023

Abstract

In 2019, two new structures ${\mathrm{\Lambda }}_b(6146)$ and ${\mathrm{\Lambda }}_b(6152)$ were observed by the LHCb Collaboration at the invariant mass spectrum of ${\mathrm{\Lambda }}_b^0{\pi }^{+}{\pi }^{-}$, which aroused a hot discussion about their inner structures. The ${\mathrm{\Lambda }}_b(6146)$ and ${\mathrm{\Lambda }}_b(6152)$ might still be molecular states because their masses are close to threshold of a $\overline{B}$ meson and a nucleon. In this work, we perform a systematical investigation of possible heavy baryonic molecular states from the $\overline{B}N$ interaction. Since the $\overline{B}N$ channel strongly couples to the ${\overline{B}}^{\ast }N$ channel, the possible $\overline{B}N-{\overline{B}}^{\ast }N$ bound states are also studied. The interaction of the system considered is described by the t-channel $\sigma$, $\pi$, $\eta$,$\omega$, and $\rho$ mesons exchanges. By solving the non-relativistic Schrödinger equation with the obtained one-boson-exchange potentials, the ${\overline{B}}^{(\ast )}N$ bound states with different quantum numbers are searched. The calculation suggests that recently observed ${\mathrm{\Lambda }}_b(6146)$ can be assigned as a P-wave $\overline{B}N$ molecular state with spin parity $J^P=3/2^{+}$ or a $\overline{B}N-{\overline{B}}^{\ast }N$ bound state. However, assignment of ${\mathrm{\Lambda }}_b(6152)$ as an F-wave $\overline{B}N$ molecular is disfavored. The ${\mathrm{\Lambda }}_b(6152)$ can be explained as meson–baryon molecular state with a small $\overline{B}N$ component. The calculation also predict the existence of two $\overline{B}N-{\overline{B}}^{\ast }N$ bound states with $J^P=1/2^{-}$ and $J^P=3/2^{-}$.