The γγ\to ϕ_iϕ_j processes in the type-III two-Higgs-doublet model
We discuss the implications of assuming a four-zero Yukawa texture and a general Higgs potential for the production of neutral Higgs boson pairs at γγcolliders through the γγ\to ϕ_iϕ_j (ϕ_i = h, H, A) reaction within the context of the two Higgs doublet model type III. Exact analytical expressions for the γγ\to ϕ_iϕ_j reaction are presented. The use of a nonlinear R_ξ-gauge, which considerably simplifies the loop calculations and renders compact analytical expressions, is stressed. We show that these processes are very sensitive to a general structure of the Higgs potential that impact the triple and quartic couplings of the scalar sector. We present results for scenarios of the parameters of the model that are still consistent with current experimental constraints. It is found that the cross sections for the γγ\to ϕ_iϕ_j processes can be up to two orders of magnitude larger than those gotten in 2HDM type I and type II. The possibility of a light CP--scalar is also studied.