Where are the higher excited $B$ and $B_s$ mesons with coupled-channel effects?

Abstract

Inspired by the newly observed $B_{s0}^*(5700)^0$, whose mass agrees well with our previous unquenched prediction for $B_s(1^3P_0)$ [Phys.~Rev.~D \textbf{109}, 116006 (2024)], we study the mass spectra and OZI-allowed two-body strong decays of the higher $3S$-, $2P$-, $2D$-, and $1F$-wave $B$ and $B_s$ mesons in the same unquenched quark model. Our results show that coupled-channel effects significantly lower the masses and modify the relative level spacings. The scalar state $B(2^3P_0)$ is strongly affected: its mass is lowered well below the quenched quark model predictions, and it mainly decays into $Bπ$. Furthermore, the mass ordering of the vector states $B(2^3D_1)$ and $B(3^3S_1)$ is reversed, and the lighter $B(2^3D_1)$ state mainly decays into $B_1(5721)π$. To test these results, the $B(2^3P_0)$ and $B(2^3D_1)$ states are worth searching for in the $Bπ$ and $B_1(5721)π$ channels, respectively. In addition, some higher excitations are predicted to be relatively narrow and can be searched for in the $B^{(*)}π$, $B^{(*)}K$, $B_1(5721)π/K$, and $B_2^*(5747)π/K$ channels. These predictions provide useful references for future experimental searches and help clarify the role of coupled-channel effects in the heavy-light meson spectrum.