# Some properties of the states at the hidden-strangeness mixed ${1 \over 2}^+ + {1 \over 2}^-$ heavy meson pair threshold in $e^+e^-$ annihilation

## TL;DR

This paper investigates the behavior of certain heavy meson pairs near threshold in electron-positron annihilation, highlighting how heavy quark spin symmetry constrains the formation of molecular states and their properties.

## Contribution

It introduces a theoretical analysis of threshold states involving hidden-strangeness heavy mesons, emphasizing the role of heavy quark spin symmetry in their production and mixing.

## Key findings

- Only one coherent combination of channels is produced in S wave due to HQSS.
- At most two threshold molecular peaks can form in the considered channels.
- Properties of these states include specific spin structures and transition behaviors.

## Abstract

The threshold behavior of $e^+ e^-$ annihilation is considered in the channels $B_{s0} \bar B_s^* + c.c.$, $B_{s1} \bar B_s + c.c.$, and $B_{s1} \bar B_s^* +c.c.$, where $B_{s0}$ and $B_{s1}$ are the excited bottom-strange $J^P=0^+$ and $J^P = 1^+$ mesons. It is argued that due to the heavy quark spin symmetry (HQSS) only one coherent combination of the first two channels is produced in the $S$ wave as well as the third channel. Thus, if there exist threshold molecular peaks in the considered channels, only two of such peaks can be formed in the annihilation. The properties of such threshold states are discussed, including the heavy-light spin structure and the related transitions to bottomonium plus light mesons, as well as mixing with the channels with and without hidden strangeness.