Search for hyperon $\mathrm{\Delta }S=\mathrm{\Delta }Q$ violating decay ${\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{-}{e}^{+}{\nu }_e$

Using a data sample of $(1.0087\pm 0.0044)\times {10}^{10}$ $J\mathrm{/}\psi$ decay events collected with the BESIII detector at the center-of-mass energy of $\sqrt{s}=3.097$ GeV, we present a search for the hyperon semileptonic decay ${\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{-}{e}^{+}{\nu }_e$ which violates the $\mathrm{\Delta }S=\mathrm{\Delta }Q$ rule. No significant signal is observed, and the upper limit on the branching fraction $\mathcal{B}({\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{-}{e}^{+}{\nu }_e)$ is determined to be $1.6\times {10}^{-4}$ at the 90% confidence level. This result improves the previous upper limit result by about one order of magnitude.