Processes $\gamma \gamma \rightarrow \phi_i\phi_j$ in Inert Higgs Doublet Models and Two Higgs Doublet Models

In this paper, we present the results for one-loop induced processes $\gamma \gamma \rightarrow \phi_i\phi_j$ with CP-even Higgses $\phi_{i,j} \equiv h,~H$ at high energy photon-photon collision, within the frameworks of Inert Higgs Doublet Models and Two Higgs Doublet Models. Total cross-sections are shown as functions of center-of-mass energies. We find that the cross-sections for the computed processes in all the models under investigations are enhanced at around the threshold of singly charged Higgs pair ($\sim 2 M_{H^\pm}$). Furthermore, the enhancement factors defined as the ratio of cross-sections of $\gamma \gamma \rightarrow \phi_i\phi_j$ in the investigated models over the corresponding ones for $\gamma \gamma \rightarrow hh$ in the Standard Model, are examined in the model's parameter space. In the Inert Higgs Doublet Models, the factors are studied in the parameter space of $(M_{H^\pm},~\mu^2_2)$ and $(M_{H^\pm},~\lambda_2)$. In the Two Higgs Doublet Models, the factors are examined in the planes of $(M_{H^\pm},~t_{\beta})$ as well as in the space of charged Higgs mass $M_{H^\pm}$ and the soft-breaking $Z_2$ parameter $m_{12}^2$. Two scenarios of $c_{\beta-\alpha} > 0$ and $c_{\beta-\alpha} < 0$ are studied in further detail. The factors give a different behavior from considering these scenarios. As a result, discriminations for the above-mentioned scenarios can be performed at future colliders.