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 Rγ h₁ as well as the signal strengths Rγ Z and Rγ γ when h₁ is identified with the observed $SM $ Higgs boson within the $2HDMcT$ delimited parameter space. More specifically, we focused on e⁺e⁻ → h₁γ process at one-loop, and analyzed how it evolves under a full set of theoretical constraints and the available experimental data, including B→ Xₛγ constraint at 95$%$ C.L. Our analysis showed that these observables are particularly sensitive to the parameters α₁, λ₇, λ₉, the trilinear Higgs couplings and to the charged Higgs masses. We found that σ (e⁺e⁻ → h₁γ) 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 Rγ h₁ is entirely correlated with both the h₁→γγ and h₁→γ Z signal strengths.