Search for lepton number violating decays of → h

Based on 7.33 fb of $\textit{e}$ $\textit{e}$ collision data collected by the BESIII detector operating at the BEPCII collider at center-of-mass energies from 4.128 to 4.226 GeV, a search for the Majorana neutrino $\textit{ν}$ is conducted in the lepton-number-violating decays of → $\textit{h}$ $\textit{h}$ $\textit{e}$ $\textit{e}$ . Here, $\textit{h}$ represents a $\textit{K}$ or $\textit{π}$ , and $\textit{h}$ represents a $\textit{π}$ , or $\textit{ϕ}$. No significant signal is observed, and the upper limits of their branching fractions at the 90% confidence level are determined to be ( → $\textit{ϕπ}$ $\textit{e}$ $\textit{e}$ ) < 6$\textit{.}$9 $\textit{×}$ 10 , ( → $\textit{ϕK}$ $\textit{e}$ $\textit{e}$ ) < 9$\textit{.}$9 $\textit{×}$ 10 , ( $\textit{→}$ $\textit{π}$ $\textit{e}$ $\textit{e}$ ) < 1$\textit{.}$3 $\textit{×}$ 10 , ( → $\textit{K}$ $\textit{e}$ $\textit{e}$ ) < 2$\textit{.}$9 × 10 , ( → $\textit{π}$ $\textit{π}$ $\textit{e}$ $\textit{e}$ ) < 2$\textit{.}$9 $\textit{×}$ 10 and ( → $\textit{K}$ $\textit{π}$ $\textit{e}$ $\textit{e}$ ) < 3$\textit{.}$4 × 10 . The Majorana neutrino is searched for with different mass assumptions within the range [0$\textit{.}$20$\textit{,}$ 0$\textit{.}$80] GeV$\textit{/c}$ in the decay of → $\textit{ϕe}$ $\textit{ν}$ with $\textit{ν}$ → $\textit{π}$ $\textit{e}$ , and the upper limits of the branching fractions at the 90% confidence level are at the level of 10 –10 , depending on the mass of the Majorana neutrino.