Search for η and η^′ invisible decays in J/ψ→η and η^′

Using a sample of (225.3±2.8)×106 J/ψ decays collected with the BESIII detector at BEPCII, searches for invisible decays of η and η^′ in J/ψ→η and η^′ are performed. Decays of →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 2.6×10^-4 for the ratio B(η→invisible) B(η→γγ) and 2.4×10^-2 for B(η^′→invisible)B(η ^′→γγ). These limits may be used to constrain light dark matter particles or spin-1 U bosons.