Higgs to $tautau$ analysis in the future $e^{+}e^{-}$ Higgs factories

The Circular Electron Positron Collider and International Linear Collider are two electron positron Higgs factories. They are designed to operate at center-of-mass energy of 240 and 250 GeV and accumulate 5.6 and 2 $ab^{-1}$ of integrated luminosity. Using CEPC official samples, the signal strength for Higgs to $tautau$ events are analyzed. The combined accuracy of the signal strength for $Hrightarrow tautau$ at CEPC achieves 0.8%. Extrapolating this analysis to the ILC setup, we conclude the ILC can reach a relative accuracy of 1.1% or 1.2%, corresponding to two benchmark settings of the beam polarization.