The Scotogenic mechanism is an appealing pathway to naturally explain the common origin of dark matter and tiny neutrino mass. However, the conventional scotogenic dark matter usually suffers stringent constraints from the non-observation of lepton flavor violation and direct detection. To generate the non-zero neutrino masses, at least two generations of dark particles are required. For example, two real scalar singlets ϕ1 and ϕ2 are involved in the inverse scotogenic model, which are odd under the Z2 symmetry. In this paper, we consider the masses of dark scalars are nearly degenerate <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math display="inline"> <msub> <mi>m</mi> <msub> <mi>ϕ</mi> <mn>1</mn> </msub> </msub> <mo>≲</mo> <msub> <mi>m</mi> <msub> <mi>ϕ</mi> <mn>2</mn> </msub> </msub> </math></EquationSource> <EquationSource Format="TEX">$ {m}_{\phi_1}\lesssim {m}_{\phi_2} $</EquationSource> </InlineEquation>, which opens new viable pathway for the generation of dark matter ϕ1, such as the coscattering process ϕ1SM → ϕ2SM and coannihilation processes ϕ1ϕ2 → SM SM via the Higgs portal or Yukawa portal interactions. We explore the parameter space to produce the correct relic density through coscattering, as well as the contrastive coannihilation channel. We then comprehensively study the constraints of dark matter from Higgs decay, direct detection, and indirect detection. For the heavier dark scalar, the three-body decay <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math display="inline"> <msub> <mi>ϕ</mi> <mn>2</mn> </msub> <mo>→</mo> <msub> <mi>ϕ</mi> <mn>1</mn> </msub> <mi>f</mi> <mover accent="true"> <mi>f</mi> <mo stretchy="true">¯</mo> </mover> </math></EquationSource> <EquationSource Format="TEX">$ {\phi}_2\to {\phi}_1f\overline{f} $</EquationSource> </InlineEquation> not only alerts the predictions of big bang nucleosynthesis and cosmic microwave background, but also leads to the observable displaced vertex signature at colliders.

Coscattering dark matter in the inverse scotogenic model

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2026年6月22日

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Ang Liu,
Zhi-Long Han,
Fei Huang,
Feng-Lan Shao,
Wei Wang

摘要

The Scotogenic mechanism is an appealing pathway to naturally explain the common origin of dark matter and tiny neutrino mass. However, the conventional scotogenic dark matter usually suffers stringent constraints from the non-observation of lepton flavor violation and direct detection. To generate the non-zero neutrino masses, at least two generations of dark particles are required. For example, two real scalar singlets ϕ₁ and ϕ₂ are involved in the inverse scotogenic model, which are odd under the Z₂ symmetry. In this paper, we consider the masses of dark scalars are nearly degenerate $m_{ϕ_{1}} ≲ m_{ϕ_{2}}$ $ {m}_{\phi_1}\lesssim {m}_{\phi_2} $ , which opens new viable pathway for the generation of dark matter ϕ₁, such as the coscattering process ϕ₁SM → ϕ₂SM and coannihilation processes ϕ₁ϕ₂ → SM SM via the Higgs portal or Yukawa portal interactions. We explore the parameter space to produce the correct relic density through coscattering, as well as the contrastive coannihilation channel. We then comprehensively study the constraints of dark matter from Higgs decay, direct detection, and indirect detection. For the heavier dark scalar, the three-body decay $ϕ_{2} \to ϕ_{1} f \bar{f}$ $ {\phi}_2\to {\phi}_1f\overline{f} $ not only alerts the predictions of big bang nucleosynthesis and cosmic microwave background, but also leads to the observable displaced vertex signature at colliders.