Physical Review Letters
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Search for Sub-GeV Invisible Particles in Inclusive Decays of $J/ψ$ to $ϕ$
Author(s): M. Ablikim et al. (BESIII Collaboration)
A search for an invisible particle, $X$, with a mass between 0 and $0.96\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, is performed in the process $J/ψ→ϕ+X$ using $(8774.0±39.4)×{10}^{6}\text{ }\text{ }J/ψ$ events collected with the BESIII detector from 2017 to 2019. The $ϕ$ meson is fully reconstructed and… [Phys. Rev. Lett. 135, 151804] Published Thu Oct 09, 2025
