Search for charged-lepton flavor violation in $\mathrm{{\rm Y}}(2S)\to {\mathrm{\ell }}^{\mp }{\tau }^{\pm }$ ($\mathrm{\ell }=e,\mu$) decays at Belle

We report a search for the charged-lepton flavor violation in $\mathrm{{\rm Y}}(2S)\to {\mathrm{\ell }}^{\mp }{\tau }^{\pm }$ ($\mathrm{\ell }=e,\mu$) decays using a $25\text{fbi}$ $\mathrm{{\rm Y}}(2S)$ sample collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($\mathcal{B}$) at 90% confidence level. We obtain the most stringent upper limits: $\mathcal{B}(\text{Ytomutau})<0.23\times {10}^{-6}$ and $\mathcal{B}(\text{Ytoetau})<1.12\times {10}^{-6}$.