Non-decoupling effects in Higgs decays in the Two Higgs Doublet Model

We study the Higgs-boson decays h → bb̄, h → γγ and h → γZ within the framework of the Two Higgs Doublet Model (THDM) in the context of the decoupling regime, together with tree level unitarity constraints. We show that when the light CP-even Higgs boson of the THDM mimics the Standard-Model Higgs boson, not only the one-loop effects to h → {γγ, γZ} but also the one-loop contribution to h → bb̄ can be used to distinguish between THDM and SM. The size of the non-decoupling effects in h → bb̄ are of the same order as in h → {γγ, γZ} and can reach 25% in both cases.