Evidence for the semileptonic decays $\hat{I}{›}_c^{+}\to \hat{I}{\pounds }^{\pm }\ddot{I}{€}^{\mp }{e}^{+}\hat{I}{½}_e$

Abstract

Using $4.5f{b}^{-1}$ of $e^{+}{e}^{-}$ collision data collected by the BESIII detector at center-of-mass energies between $4.600$ and $4.699GeV$, we search for the semileptonic decays $\hat{I}{›}_c^{+}\to \hat{I}{\pounds }^{+}\ddot{I}{€}^{-}{e}^{+}\hat{I}{½}_e$ and $\hat{I}{›}_c^{+}\to \hat{I}{\pounds }^{-}\ddot{I}{€}^{+}{e}^{+}\hat{I}{½}_e$ for the first time. Assuming their branching fractions are equal under isospin symmetry, evidence for $\hat{I}{›}_c^{+}\to \hat{I}{\pounds }^{\pm }\ddot{I}{€}^{\mp }{e}^{+}\hat{I}{½}_e$ is reported with a significance of $3.6\ddot{I}ƒ$. The corresponding branching fraction is measured to be $\mathcal{B}(\hat{I}{›}_c^{+}\to \hat{I}{\pounds }^{\pm }\ddot{I}{€}^{\mp }{e}^{+}\hat{I}{½}_e)=(7.7_{-2.3_{stat.}}^{+2.5}\pm 1.3_{syst.})\times 10^{-4}$, which is consistent with quark model predictions within two standard deviations.