Measuring BR($h\to {\tau }^{+}{\tau }^{-}$) at the ILC: a full simulation study

We evaluate the expected measurement accuracy of the branching ratio of the Standard Model Higgs boson decaying into tau pairs at the ILC with a full simulation of the ILD detector concept. We assume a Higgs mass of 125 GeV, a branching ratio of BR($h\to {\tau }^{+}{\tau }^{-}$) = 6.32%, a beam polarization of electron (positron) of -0.8(+0.3), and an integrated luminosity of 250 fb${}^{-1}$. The Higgs-strahlung process $e^{+}{e}^{-}\to Zh$ with $Z \to q\overline{q}$ is analyzed. We estimate the measurement accuracy of the branching ratio $\Delta (\sigma \times $\mathrm{B}\mathrm{R}$) / (\sigma \times $\mathrm{B}\mathrm{R}$)$ to be 3.4% with using a multivariate analysis technique.