Probing the Phenomenology of Dark Matter from Decoupled Freeze-Out
Abstract
We consider a model of dark matter where the mediator corresponds to a superposition of a scalar and pseudoscalar, and the scenario where, after reheating, the number densities of the dark sector particles, i.e. the dark matter and the mediators, are negligible. If the coupling of the mediators to the Standard Model is feeble, but the coupling to the dark matter is large enough, the dark sector may reach equilibrium at a temperature distinct from that of the thermal bath. The relic density is then said to be obtained via decoupled freeze out (DFO). We focus on the s-wave annihilation scenario, which particularly benefits from the DFO mechanism by evading standard CMB limits while still yielding indirect detection signals. We calculate the relic density by solving a set of four coupled Boltzmann equations for the number densities of the dark sector particles and the energy transfer from the light to dark sector. We finally perform a thorough analysis of experimental bounds on this scenario, namely from indirect detection and the CMB, as well as from BBN, and find that, while there are considerable constraints on the parameter space where the correct relic density is obtained, a viable region remains to be explored.
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BibTeX
@article{belanger2026probing,
title = {{Probing the Phenomenology of Dark Matter from Decoupled Freeze-Out}},
author = {Geneviève Bélanger and Aoife Bharucha and Sreemanti Chakraborti and Rashidul Islam and Sophie Mutzel},
journal = {Journal of High Energy Physics},
year = {2026},
month = jun,
doi = {10.1007/jhep06(2026)131},
eprint = {2511.14635},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05396412v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Probing the Phenomenology of Dark Matter from Decoupled Freeze-Out
AU - Geneviève Bélanger
AU - Aoife Bharucha
AU - Sreemanti Chakraborti
AU - Rashidul Islam
AU - Sophie Mutzel
PY - 2026
DA - 2026/06/11
JO - Journal of High Energy Physics
DO - 10.1007/jhep06(2026)131
UR - https://hal.science/hal-05396412v1
AB - We consider a model of dark matter where the mediator corresponds to a superposition of a scalar and pseudoscalar, and the scenario where, after reheating, the number densities of the dark sector particles, i.e. the dark matter and the mediators, are negligible. If the coupling of the mediators to the Standard Model is feeble, but the coupling to the dark matter is large enough, the dark sector may reach equilibrium at a temperature distinct from that of the thermal bath. The relic density is then said to be obtained via decoupled freeze out (DFO). We focus on the s-wave annihilation scenario, which particularly benefits from the DFO mechanism by evading standard CMB limits while still yielding indirect detection signals. We calculate the relic density by solving a set of four coupled Boltzmann equations for the number densities of the dark sector particles and the energy transfer from the light to dark sector. We finally perform a thorough analysis of experimental bounds on this scenario, namely from indirect detection and the CMB, as well as from BBN, and find that, while there are considerable constraints on the parameter space where the correct relic density is obtained, a viable region remains to be explored.
SN - 1126-6708
SN - 1029-8479
ER -