Possible hidden-bottom molecular pentaquarks from $P$-wave $\hat{I}{›}_b{B}^{(\ast )}/\hat{I}{\pounds }_b^{(\ast )}{B}^{(\ast )}$ interactions

Abstract

In this work, we perform a systematic investigation of the hidden-bottom molecular pentaquark states, encompassing both bound states and resonances, which originate from the $P$-wave interactions between ground-state bottom baryons ($\hat{I}{›}_b$, $\hat{I}{\pounds }_b^{(\ast )}$) and ground-state antibottom mesons ($B^{(\ast )}$). Adopting the one-boson-exchange model and including the coupled-channel effects, we derive the effective potentials for all allowed quantum numbers $I(J^P)=1/2(1/2^{+})$, $1/2(3/2^{+})$, $1/2(5/2^{+})$, $1/2(7/2^{+})$, $3/2(1/2^{+})$, $3/2(3/2^{+})$, $3/2(5/2^{+})$, and $3/2(7/2^{+})$. We then solve the coupled-channel Schrödinger equations to search for the bound-state solutions and perform the phase-shift analyses to identify resonance poles. Our results reveal a rich spectrum of positive-parity hidden-bottom molecular pentaquark candidates. In the isospin $I=1/2$ sector, we find several loosely bound states and associated resonances, particularly in the $\hat{I}{\pounds }_b{B}^{\ast }$ and $\hat{I}{\pounds }_b^{\ast }{B}^{\ast }$ channels, where the coupled-channel dynamics plays an essential role in their formation. In the isospin $I=3/2$ sector, the attraction is generally weaker because of the isospin factors. Nevertheless, we still obtain the loosely bound states and resonances, such as the $\hat{I}{\pounds }_b^{\ast }{B}^{\ast }$ states with $J^P=3/2^{+}$, $5/2^{+}$, and $7/2^{+}$. The prominence of high-spin partial waves, for instance the ${}^6{P}_J$ components, underscores the importance of the spin-spin and tensor interactions. Our predictions provide a comprehensive and systematic spectrum of the $P$-wave hidden-bottom molecular pentaquark states and offer clear guidance for future experimental searches at LHCb and Belle~II.

18 pages, 8 figures

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