${\rm Y}(6S)$ and triangle singularity in $e^{+}{e}^{-}\to B_1(5721)\bar{B}\to Z_b(10610)\pi$

Abstract

We discuss the possibility that production of final states with bottomonium and light mesons at the peak ${\rm Y}(6S)$ 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, ${\rm Y}(nS)\pi \pi$ and $h_b(kP)\pi \pi$. The discussed mechanism also predicts a distinct pattern for production of hidden-bottom states at the ${\rm Y}(6S)$ energy that can be tested by experiment.

Comments: 11 pages, 3 figures