Search for the lepton number violating decay ${\Sigma }^{-}\to p{e}^{-}{e}^{-}$ and the rare inclusive decay ${\Sigma }^{-}\to {\Sigma }^{+}X$

Using a data sample of $\left(1310.6±7.0\right)×{10}^{6}\text{}\text{}J/\psi $ events taken with the BESIII detector at the center-of-mass energy of 3.097 GeV, we search for the first time for the lepton number violating decay ${\Sigma }^{-}\to p{e}^{-}{e}^{-}$ and the rare inclusive decay ${\Sigma }^{-}\to {\Sigma }^{+}X$, where $X$ denotes any possible particle combination. The ${\Sigma }^{-}$ candidates are tagged in $J/\psi \to \overline{\Sigma }\left(1385{\right)}^{+}{\Sigma }^{-}$ decays. No signal candidates are found, and the upper limits on the branching fractions at the 90% confidence level are determined to be $B\left({\Sigma }^{-}\to p{e}^{-}{e}^{-}\right)<6.7×{10}^{-5}$ and $B\left({\Sigma }^{-}\to {\Sigma }^{+}X\right)<1.2×{10}^{-4}$.