One of the detector benchmark processes investigated for the SiD Detailed Baseline Design (DBD) is given by: e+e- -> ttH, where H is the Standard Model Higgs boson of mass 125 GeV. The study is carried out at a centre-of-mass energy of 1 TeV and assu
ming an integrated luminosity of 1 ab-1. The physics aim is a direct measurement of the top Yukawa coupling at the ILC. Higgs boson decays to beauty quark-antiquark pairs are reconstructed. The investigated final states contain eight jets or six jets, one charged lepton and missing energy. Additionally, four of the jets in signal events are caused by beauty quark decays. The analysis is based on a full simulation of the SiD detector using GEANT4. Beam-related backgrounds from gammagamma -> hadrons interactions and incoherent e+e- pairs are considered. This study addresses various aspects of the detector performance: jet clustering in complex hadronic final states, flavour-tagging and the identification of high energy leptons.
The investigation of the properties of a Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state, is currently one of the most compelling arguments for building a linear collider. We de
monstrate that the large Higgs boson production cross section at a 3 TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H rightarrow b^{-}b, H rightarrow cc^{-} and H rightarrow {mu}{mu} can be measured with a statistical uncertainty of 0.22%, 3.2% and 15%, respectively.
