Speaker
Description
The two Higgs doublet model without any ad hoc symmetries, in general should have extra Yukawa interactions which cause exotic interactions such as flavor changing neutral processes. Effects of the extra Yukawa interactions can also appear in
couplings of the 125 GeV Higgs boson ($h$) via fermion loop contributions. In this talk, we calculate the $hZZ$ coupling expected to be measured with $\mathcal{O}(1) \%$ accuracy at future lepton collider experiments, at the one-loop level by the on-shell renormalization scheme, and evaluate how the $hZZ$ coupling depends on the mass of extra Higgs bosons and the extra Yukawa coupling $\rho_{tt}$. We find that if $\rho_{tt} \cos\gamma < 0$, where $\gamma$ is a mixing angle of CP-even Higgs bosons, the $\rho_{tt}$ effect induced top loop contribution cancels extra Higgs boson loop contributions and one may have alignment without decoupling, but exotic scalar bosons could have masses at several hundred GeV. We also discuss whether future precision coupling measurements can give stronger bound on $\rho_{tt}$ than the current bound from flavor experiments.
