Higgs photon associated production in a Two Higgs Doublet Type-II Seesaw Model at future electron-positron colliders

We studied the one-loop prediction for the single production of a Higgs-like boson in association with a photon in electron-positron collisions in the context of two Higgs doublet type-II seesaw model (2HDMcT). We explored to what extent the new scalars in the (2HDMcT) spectrum affect its production cross-section, the ratio R_γ h_1 as well as the signal strengths R_γ Z and R_γγ when h_1 is identified with the observed SM Higgs boson within the 2HDMcT delimited parameter space. More specifically, we focused on e^+e^- → h_1γ process at one-loop, and analyzed how it evolves under a full set of theoretical constraints and the available experimental data, including B→ X_sγ constraint at 95% C.L. Our analysis showed that these observables are particularly sensitive to the parameters α_1, λ_7, λ_9, the trilinear Higgs couplings and to the charged Higgs masses. We found that σ (e^+e^- → h_1γ) can significantly be enhanced up to 8.1 10^-2 fb, so exceeding the Standard Model prediction. Additionally, as a byproduct, we also found that R_γ h_1 is entirely correlated with both the h_1→γγ and h_1→γ Z signal strengths.