Measurement of the branching fraction of $\psip \to \omega \eta \eta$

Abstract

Using a sample of (2.712 $\pm$ 0.014)$\times 10^{9}$ $\psip$ events collected with the BESIII detector at the BEPCII collider in 2009, 2012, and 2021, the decay $\psip \to \omega \eta \eta $ is observed for the first time. The branching fraction of the $\psi(3686)\to\omega\eta\eta$ decay is measured to be (1.65 $\pm$ 0.02 $\pm$ 0.21)$\times 10^{-5}$, where the first uncertainty is statistical and the second systematic. Clear structures associated with the well-established $\omega(1420)$ and $f_{0}(1710)$ resonances are observed in the $\omega\eta$ and $\eta\eta$ invariant-mass spectra, respectively.