Freeze-in Asymmetric Dark Matter with a Dual-Role Scalar: CP Violation and Symmetric-Component Depletion
Abstract
We present a minimal, predictive scenario for asymmetric fermionic dark matter (DM) generated through freeze-in. The standard model (SM) is extended by a Dirac fermion ψ that serves as the DM candidate, an auxiliary Dirac fermion χ, a real scalar mediator ϕ, and a heavier real scalar S, all stabilized by a Z2 × Z2' discrete symmetry. The DM asymmetry is generated through the CP-violating out-of-equilibrium decays of the mediator ϕ, while the heavier scalar S plays a dual role: it generates the physical CP-violating phase required for the asymmetry through its interference with ϕ, and it mediates the annihilation of the symmetric component of the DM population. We solve the coupled Boltzmann equations for the asymmetric yield Y- and the total yield YΣ, and identify the scaling relations Y-∞ ∝ μ2 ε / mϕ and ΩDM h2 ∝ mψ μ2 ε / mϕ, which we verify numerically. The observed relic abundance ΩDM h2 ≃ 0.12 is naturally reproduced for a wide range of parameters; in particular, for ε = 10−6 and mϕ= 200~GeV, the correct relic density is obtained for μ≈ 2.7 × 10−9~GeV and mψ≈ 40~GeV. We further confront the model with current experimental constraints, including direct detection, indirect detection, collider searches, and DM self-interactions, and show that the predicted signals lie far below the sensitivity of current experiments. This scenario provides a self-consistent and testable realization of asymmetric fermionic DM within the freeze-in framework.
Related
- Asymmetric frequency conversion and violation of Kirchhoff’s law of thermal radiation in phased Floquet metasurfaces
- A Nonlinear Two-Sheath Circuit Model for Low-Pressure Symmetric and Asymmetric Capacitively Coupled Radio-Frequency Plasmas
- Near-unit-root persistence of symmetric and asymmetric stable autoregressive sequences
- A relook at a low reheating temperature: Freeze-in versus Freeze-out
- Kaon Portal to Freeze-in Dark Matter
BibTeX
@misc{zakeri2026freezein,
title = {{Freeze-in Asymmetric Dark Matter with a Dual-Role Scalar: CP Violation and Symmetric-Component Depletion}},
author = {S. Peyman Zakeri},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.04354},
eprint = {2610.04354},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.04354},
}
RIS
TY - UNPB
TI - Freeze-in Asymmetric Dark Matter with a Dual-Role Scalar: CP Violation and Symmetric-Component Depletion
AU - S. Peyman Zakeri
PY - 2026
DA - 2026/10/03
PB - arXiv
DO - 10.48550/arxiv.2610.04354
UR - https://arxiv.org/abs/2610.04354
AB - We present a minimal, predictive scenario for asymmetric fermionic dark matter (DM) generated through freeze-in. The standard model (SM) is extended by a Dirac fermion ψ that serves as the DM candidate, an auxiliary Dirac fermion χ, a real scalar mediator ϕ, and a heavier real scalar S, all stabilized by a Z_2 × Z_2' discrete symmetry. The DM asymmetry is generated through the CP-violating out-of-equilibrium decays of the mediator ϕ, while the heavier scalar S plays a dual role: it generates the physical CP-violating phase required for the asymmetry through its interference with ϕ, and it mediates the annihilation of the symmetric component of the DM population. We solve the coupled Boltzmann equations for the asymmetric yield Y_- and the total yield Y_Σ, and identify the scaling relations Y_-^∞ ∝ μ^2 ε / m_ϕ and Ω_DM h^2 ∝ m_ψ μ^2 ε / m_ϕ, which we verify numerically. The observed relic abundance Ω_DM h^2 ≃ 0.12 is naturally reproduced for a wide range of parameters; in particular, for ε = 10^−6 and m_ϕ= 200~GeV, the correct relic density is obtained for μ≈ 2.7 × 10^−9~GeV and m_ψ≈ 40~GeV. We further confront the model with current experimental constraints, including direct detection, indirect detection, collider searches, and DM self-interactions, and show that the predicted signals lie far below the sensitivity of current experiments. This scenario provides a self-consistent and testable realization of asymmetric fermionic DM within the freeze-in framework.
ER -