Search for $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ invisible decays in $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\phi}\ensuremath{\eta}$ and $\ensuremath{\phi}{\ensuremath{\eta}}^{\ensuremath{'}}$

Search for $η$ and $η^{'}$ invisible decays in $J / ψ \to ϕ η$ and $ϕ η^{'}$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. D 87, 012009 – Published 24 January 2013

Abstract

Using a sample of $(225.3 \pm 2.8) \times 10^{6}$ $J / ψ$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $η$ and $η^{'}$ in $J / ψ \to ϕ η$ and $ϕ η^{'}$ are performed. Decays of $ϕ \to K^{+} K^{-}$ are used to tag the $η$ and $η^{'}$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.6 \times 10^{- 4}$ for the ratio $\frac{B (η \to invisible)}{B (η \to γ γ)}$ and $2.4 \times 10^{- 2}$ for $\frac{B (η^{'} \to invisible)}{B (η^{'} \to γ γ)}$ . These limits may be used to constrain light dark matter particles or spin-1 $U$ bosons.