Enhancement of h→γγ in the Two Higgs Doublet Model Type I

We show that in the Two Higgs Doublet Model (THDM) Type I the partial decay width Γ(h→γγ) can be considerably larger than in Type II, due to light charged scalars with MH±≈100 GeV, which are not yet excluded in Type I. A possible enhancement of the width compared to the SM is analyzed for different Higgs potentials, subject to constraints from tree-level unitarity, vacuum stability and electroweak precision tests.