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Main Authors: Azari, F., Haghighat, M.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.27471
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author Azari, F.
Haghighat, M.
author_facet Azari, F.
Haghighat, M.
contents We investigate the phenomenology of the Standard Model extended by a real gauge-singlet scalar field, focusing on exotic Higgs decay channels. For a light scalar mass in the range \(0 < m_ϕ < 40\) GeV, the Higgs boson can decay to both two and three scalar final states. We derive analytical expressions for these decay rates and impose a global constraint on the model parameters by requiring that their sum does not exceed the total Standard Model Higgs boson decay width. This requirement translates into a fourth-order inequality with respect to the singlet vacuum expectation value, \(v_ϕ\). We demonstrate that satisfying this inequality imposes an upper bound of \(\cos θ< 0.12 - 0.13\) across the entire mass range, providing a complementary constraint to existing direct search limits. Utilizing stronger independent constraints on the mixing (e.g., \(\cos θ< 0.1\)), we then predict upper bounds on the individual exotic decay rates as a function of \(m_ϕ\) as \(Γ_{h \rightarrow ϕϕ} < 0.06\) MeV and \(Γ_{h \rightarrow ϕϕϕ} < 5 \times 10^{- 6}\) MeV, respectively.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27471
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publishDate 2026
record_format arxiv
spellingShingle Constraints on a Light Singlet Scalar from Combined Exotic Higgs Decays
Azari, F.
Haghighat, M.
High Energy Physics - Phenomenology
High Energy Physics - Theory
We investigate the phenomenology of the Standard Model extended by a real gauge-singlet scalar field, focusing on exotic Higgs decay channels. For a light scalar mass in the range \(0 < m_ϕ < 40\) GeV, the Higgs boson can decay to both two and three scalar final states. We derive analytical expressions for these decay rates and impose a global constraint on the model parameters by requiring that their sum does not exceed the total Standard Model Higgs boson decay width. This requirement translates into a fourth-order inequality with respect to the singlet vacuum expectation value, \(v_ϕ\). We demonstrate that satisfying this inequality imposes an upper bound of \(\cos θ< 0.12 - 0.13\) across the entire mass range, providing a complementary constraint to existing direct search limits. Utilizing stronger independent constraints on the mixing (e.g., \(\cos θ< 0.1\)), we then predict upper bounds on the individual exotic decay rates as a function of \(m_ϕ\) as \(Γ_{h \rightarrow ϕϕ} < 0.06\) MeV and \(Γ_{h \rightarrow ϕϕϕ} < 5 \times 10^{- 6}\) MeV, respectively.
title Constraints on a Light Singlet Scalar from Combined Exotic Higgs Decays
topic High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2604.27471