Full simulation study of the higgs branching ratio into tau lepton pairs at the ILC with √s = 500 GeV

We evaluate the expected measurement accuracy of the branching ratio of the Standard Model Higgs boson decaying into tau lepton pairs h → τ⁺τ⁻ at the ILC with a center-of-mass energy of √s = 500 GeV with a full simulation of the ILD detector. We assume a Higgs mass of M_h = 125 GeV, a branching ratio of BR(h → τ⁺τ⁻) = 6.32 %, beam polarizations of P (e⁻, e⁺) = (−0.8, +0.3), and an integrated luminosity of ∫ L dt = 500 fb⁻¹. The Higgs-strahlung process e⁺e⁻ → Zh with Z → qq and the W W-fusion process e⁺e⁻ → ννh are expected to be the most sensitive channels at √s = 500 GeV. Using a multivariate analysis technique, we estimate the expected relative measurement accuracy of the branching ratio ∆(σ · BR)/(σ · BR) to be 4.7% and 7.4% for the qqh and ννh final states, respectively. The results are cross-checked using a cut-based analysis.