Higgs photon associated production in a two Higgs doublet type-II seesaw model at future electron-positron colliders

We study the one-loop prediction for the single production of a SM-like Higgs boson in association with a photon in electron-positron collisions in the context of the two Higgs doublet type-II seesaw model (2HDMcT). We explore to what extent the new scalars in the 2HDMcT spectrum affect its production cross-section, the ratio Rγ h₁ R γ h 1 as well as the signal strengths Rγ Z R γ Z and Rγ γ R γ γ when h₁ h 1 is identified with the observed SM Higgs boson within the 2HDMcT delimited parameter space. More specifically, we focus on e⁺e⁻ → h₁γ e + e - → h 1 γ process at one-loop, and analyzed how it evolves under a full set of theoretical constraints and the available experimental data, including B→ Xₛγ B → X s γ limit at 95 $$%$$ % C.L. Our analysis shows that these observables are strongly dependent on the parameters of the model, especially the mixing angel α ₁ α 1 , the potential parameters λ ₇ λ 7 , λ ₉ λ 9 , the trilinear Higgs couplings, with a noticeable sensitivity to α ₁ α 1 . We found that σ (e⁺e⁻ → h₁γ ) σ ( e + e - → h 1 γ ) can significantly be enhanced up to 8.1\,\,× 10⁻² 8.1 × 10 - 2 fb, thus exceeding the Standard Model prediction. Additionally, as a byproduct, we also observed that Rγ h₁ R γ h 1 is entirely correlated with both the h₁→ γ γ h 1 → γ γ and h₁→ γ Z h 1 → γ Z signal strengths.