Exotic Higgs decay via charged Higgs

Abstract: The most common search channel for heavy neutral Higgses in models with an extension of the Standard Model Higgs sector is A/H⁰ → ττ , which becomes ineffective when new decay modes of A/H⁰ open. In this paper, we analyzed two such channels involving charged Higgses in the final states: A/H⁰ → W^±H^∓ and H⁰ → H⁺H⁻. With the consequent decay of H^± → τν, we found that the limits for σ × BR(gg → A/H⁰ → W^±H^∓) × BR(H^± → τν) vary from 30 to 10fb for m_A/H⁰ between 300 and 1000GeV for 95% C.L. exclusion, and about 80 to 30 fb for 5σ discovery. For H⁺H⁻ mode, 95% C.L. limits on σ × BR(gg → H⁰ → H⁺H⁻) × BR²(H^± → τν) vary from 9 to 4 fb for m_H⁰ between 400 and 1000 GeV, while the 5σ reach is about 20 to 10 fb. We further interpret the cross section limits in the Type II 2HDM parameter space. While A → W^±H^∓ offers great sensitivity in both sin(β − α) versus tan β and m_A versus tan β parameter space, H⁰ → H⁺H⁻ can cover most of the parameter space for H⁰. Reach in H⁰ → W^±H^∓ is more limited, especially for m_H⁰> 2m_H±. It is, however, complementary to H⁰ → H⁺H⁻ when BR(H⁰ → H⁺H⁻) is accidentally suppressed.