Unitarity Bound on Extended Higgs Sector with Higher Dimensional Operator

We study the perturbative unitarity bound given by higher dimensional bosonic operators up to dim-6 for the two-Higgs-doublet model (2HDM). They lead to new physics beyond the Standard Model. We point out that such operators can lead to a larger cross-section in the vector boson fusion channels for the scalars, compared to the tree-level 2HDM. We have obtained limits on a few bosonic operators up to dim-6 for 2HDM, by ensuring unitarity of the S-matrix.