Search for a dark baryon in the ${\Xi }^{-}\to {\pi }^{-}+\mathrm{invisible}$ decay

BESIII Collaboration, M. Ablikim, M. N. Achasov +689

A search for a dark baryon is performed for the first time in the two-body decay ${\Xi }^{-}\to {\pi }^{-}+\mathrm{invisible}$ using $(10.087\pm 0.044)\times 10^9$ $J/\psi$ events collected at…