Search for a dark baryon in the $\hat{I}{ž}^{-}\to \ddot{I}{€}^{-}+\mathrm{invisible}$ 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 $\hat{I}{ž}^{-}\to \ddot{I}{€}^{-}+\mathrm{invisible}$ using $(10.087\pm 0.044)\times 10^9$ $J/\ddot{I}ˆ$ events collected…