Search for the lepton number violating process $\hat{I}{ž}^{-}\to \hat{I}{\pounds }^{+}{e}^{-}{e}^{-}+c.c.$

Abstract

We present a search for the lepton number violating decay $\hat{I}{ž}^{-}\to \hat{I}{\pounds }^{+}{e}^{-}{e}^{-}+c.c.$ with $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected by the BESIII detector at the BEPCII collider. Employing a blind analysis strategy, no significant signal is observed above the expected background yield. The upper limit on the branching fraction is determined to be $\mathrm{Br}(\hat{I}{ž}^{-}\to \hat{I}{\pounds }^{+}{e}^{-}{e}^{-}+c.c.)<2.0\times 10^{-5}$ at the $90\%$ confidence level.