中国物理学会高能物理分会第十三届全国粒子物理学术会议（2021）

BESIII has collected 448 M $\psi(3686)$ events and 10 B $J/\psi$ events. The huge data sample provide an excellent chance to search for new physics. We report the search for the decay $J/\psi\to\gamma + invisible$, which is predicted by next-to-minimal supersymmetric model. Without significant signal found, we gave about 6 times better upper limits than previous CLEO-c’s results. We also search for the J/psi rare weak decay to $\bar D^0\pi^0, \bar D^0 \eta, \bar D^0 \rho^0, D^-\pi^+, D^-\rho^+$ and $D^-e^+\nu_e +c.c.$, and present the most stringent constraints of $10^{-6}$ at 90\% confidence level. We also report the preliminary result of the first search for the invisible decay of $\Lambda$, which is predicted by the mirror matter model and could explain the $4\sigma$ discrepancy in neutron lifetime measurement between beam method and bottle method.