Spectator Dark Matter and the Higgs Portal
Abstract
Light scalar spectators generically acquire large stochastic fluctuations during inflation, which can lead to a catastrophic overproduction of dark matter if the resulting primordial condensate survives until late times. We show that this inflationary memory can be sufficiently suppressed by an extremely feeble Higgs portal interaction with sub-freeze-in couplings (10−28 ≲ λHS ≲ 10−9). The Higgs portal induces both a radiative self-interaction for the spectator as well as a thermal mass, both of which can lead to early onset of oscillations and efficient redshifting of the condensate's energy density without thermalizing the spectator or destroying the condensate. The Higgs portal also alters the stochastic equilibrium distribution of the spectator fluctuations, leading to a suppression of the field variance relative to an isolated spectator. We include a detailed treatment of the possibility that inflation may not have lasted sufficiently long for the spectator to reach its equilibrium distribution of fluctuations, finding the major constraint on such a scenario to come from isocurvature, which requires N ≳1010 e-folds. We also consider the addition of a non-minimal gravitational coupling, which extends the parameter space significantly. This model generally favors sub-GeV light dark matter (0.1 eV ≲ mS ≲ 10 GeV) and in the absence of non-minimal gravity it also favors low reheating temperatures. While this mechanism can supply the entire relic abundance with sub-freeze-in portal couplings, it also naturally provides a suppressed initial condition for standard Higgs portal freeze-in.
Related
- Gravitational Dark Matter Production from Spectator Field in R2-Higgs Inflation
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BibTeX
@misc{henrich2026spectator,
title = {{Spectator Dark Matter and the Higgs Portal}},
author = {Stephen E Henrich and Yann Mambrini and Keith A Olive},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07331},
eprint = {2610.07331},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05829770v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Spectator Dark Matter and the Higgs Portal
AU - Stephen E Henrich
AU - Yann Mambrini
AU - Keith A Olive
PY - 2026
DA - 2026/10/05
PB - HAL
DO - 10.48550/arxiv.2610.07331
UR - https://hal.science/hal-05829770v1
AB - Light scalar spectators generically acquire large stochastic fluctuations during inflation, which can lead to a catastrophic overproduction of dark matter if the resulting primordial condensate survives until late times. We show that this inflationary memory can be sufficiently suppressed by an extremely feeble Higgs portal interaction with sub-freeze-in couplings (10^−28 ≲ λ_HS ≲ 10^−9). The Higgs portal induces both a radiative self-interaction for the spectator as well as a thermal mass, both of which can lead to early onset of oscillations and efficient redshifting of the condensate's energy density without thermalizing the spectator or destroying the condensate. The Higgs portal also alters the stochastic equilibrium distribution of the spectator fluctuations, leading to a suppression of the field variance relative to an isolated spectator. We include a detailed treatment of the possibility that inflation may not have lasted sufficiently long for the spectator to reach its equilibrium distribution of fluctuations, finding the major constraint on such a scenario to come from isocurvature, which requires N ≳10^10 e-folds. We also consider the addition of a non-minimal gravitational coupling, which extends the parameter space significantly. This model generally favors sub-GeV light dark matter (0.1 eV ≲ m_S ≲ 10 GeV) and in the absence of non-minimal gravity it also favors low reheating temperatures. While this mechanism can supply the entire relic abundance with sub-freeze-in portal couplings, it also naturally provides a suppressed initial condition for standard Higgs portal freeze-in.
ER -