$\Upsilon(6S)$ and triangle singularity in $e^+e^- \to B_1(5721) \bar B \to Z_b(10610) \, \pi$

TL;DR

This paper proposes that the observed production of bottomonium and light mesons at the $S)$ resonance is due to a triangle singularity involving heavy meson pairs, offering a new explanation for experimental data.

Contribution

It introduces a novel mechanism involving a triangle singularity at the heavy meson threshold to explain $S)$ production phenomena, linking it to the formation of $Z_b(10610)$.

Findings

Predicts a specific pattern for hidden-bottom state production at $S)$

Explains the enhanced production of $S)$ channels with bottomonium states

Provides a testable hypothesis for experimental verification

Abstract

We discuss the possibility that production of final states with bottomonium and light mesons at the peak $\Upsilon(6S)$ in the $e^+e^-$ annihilation at approximately 11.00 GeV is in fact due to a triangular singularity at the threshold of the heavy meson pair production $B_1(5721) \bar B + c.c.$ through the process $e^+e^- \to B_1(5721) \bar B \to Z_b(10610) \, \pi$. The presence of the hidden-bottom resonance $Z_b(10610)$ then explains the observed enhanced production of the final channels with both ortho- and para- bottomonium states, $\Upsilon(nS) \pi \pi$ and $h_b(kP) \pi \pi$. The discussed mechanism also predicts a distinct pattern for production of hidden-bottom states at the $\Upsilon(6S)$ energy that can be tested by experiment.