The 17 MeV Anomaly in Beryllium Decays and $U(1)$ Portal to Dark Matter

Chian-Shu Chen, Guey-Lin Lin, Yen-Hsun Lin +1

The experiment of Krasznahorkay \textit{et al} observed the transition of a ${}^8\mathrm{Be}$ excited state to its ground state and accompanied by an emission of $e^{+}{e}^{-}$ pair with…