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

In 2019, two new structures Λ${}_b$(6146) and Λ${}_b$(6152) were observed by the LHCb Collaboration at the invariant mass spectrum of Λ${}_b^0$π${}^{+}$π${}^{-}$, which aroused a hot discussion about their inner structures. The Λ${}_b$(6146) and Λ${}_b$(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 σ, π, η,ω, and ρ 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 Λ${}_b$(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 Λ${}_b$(6152) as an F-wave $\overline{B}N$ molecular is disfavored. The Λ${}_b$(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${}^{-}$.