Searching for Light Boson via the Yukawa Process at Lepton Colliders

I will present the prospect of Yukawa production process of a light boson which can exist in an extended Higgs sector. A particularly interesting case is the light pseudoscalar in Type-X two Higgs doublet model which can explain the anomalous magnetic moment of muon at large $\tan\beta$. Considering ILC “Higgs factory” with center-of-mass energy of 250 GeV, we show that the available parameter space can be fully examined by the (tau) Yukawa process at 5$\sigma$ with an integrated luminosity of $2000 \rm{fb}^{−1}$. We also demonstrate the mass reconstruction of such a light particle which helps to minimize the background events considerably. This proceeding is based on ref [1].