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

TL;DR

This paper studies the production of the exotic $X_b$ state via radiative decays of $S$ and $S$ bottomonium states, using meson loop mechanisms and effective Lagrangian calculations, predicting measurable branching ratios.

Contribution

It introduces a detailed calculation of $X_b$ production rates in $S$ and $S$ decays considering meson loops, providing predictions for experimental detection.

Findings

Branching ratios estimated at $10^{-7}$ to $10^{-6}$.

Rescattering mechanisms significantly contribute to $X_b$ production.

Predicted rates are within reach of BelleII experiment.

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 $B {\bar B}^*$ molecular state. Two kinds of meson loops of $B^{(*)}{\bar B}^{(*)}$ and $B_1^{\prime}{\bar B}^{(*)}$ 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 $10^{-7} \sim 10^{-6}$. Such sizeable branching ratios might be accessible at BelleII, which would provide important clues to the inner structures of the exotic state $X_b$.