Search for invisible decays of $ω$ and $ϕ$ with $J/ψ$ data at BESIII

Abstract

Using a data sample of $(1310.6 \pm 7.0)\times 10^6$ $J/ψ$ events collected with the BESIII detector operating at the BEPCII collider, we perform the first experimental search for invisible decays of a light vector meson ($V=ω,ϕ$) via $J/ψ\to V η$ decays. The decay of $η\to π^+π^-π^0$ is utilized to tag the $V$ meson decaying into the invisible final state. No evidence for a significant invisible signal is observed, and the upper limits on the ratio of branching fractions at the 90\% confidence level are determined to be $\frac{\mathcal{B}(ω\rightarrow \rm{invisible})}{\mathcal{B}(ω\to π^+π^-π^0)} < 8.1 \times 10^{-5}$ and $\frac{\mathcal{B}(ϕ\to \rm{invisible})}{\mathcal{B}(ϕ\to K^+K^-)} < 3.4\times 10^{-4}$. By using the world average values of $\mathcal{B}(ω\to π^+π^-π^0)$ and $\mathcal{B}(ϕ\to K^+K^-)$, the upper limits on the decay branching fractions at the $90\%$ confidence level are set as $\mathcal{B}(ω\to \rm{invisible})< 7.3 \times 10^{-5}$ and $\mathcal{B}(ϕ\to \rm{invisible})< 1.7\times 10^{-4}$, respectively.

10 pages, 6 figures