Production of $X_b$ via $Υ(5S, 6S)$ radiative decays

Abstract: We investigate the production of $X_b$ in the process $\Upsilon(5S,6S)\to \gamma X_b$, where $X_b$ is assumed to be a $B {\bar B}<sup>*$ molecular state. Two kinds of meson loops of $B^{(*)}{\bar B}<sup>{(*)}$ and $B_1^{{\prime}{\bar} B}<sup>{(*)}$ were considered. To explore the rescattering mechanism, we calculated the relevant branching ratios using the effective Lagrangian based on the heavy quark symmetry. The branching ratios for the $\Upsilon(5S\,,6S) \to \gamma X_b$ were found to be at the orders of $10^{-7} \sim 10<sup>{-6}$. Such sizeable branching ratios might be accessible at BelleII, which would provide important clues to the inner structures of the exotic state $X_b$.