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Main Authors: Ferrante, Steven, Perelstein, Maxim, Yu, Bingrong
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.16731
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author Ferrante, Steven
Perelstein, Maxim
Yu, Bingrong
author_facet Ferrante, Steven
Perelstein, Maxim
Yu, Bingrong
contents We consider the cosmological history of a weakly interacting massive particle (WIMP) coupled to a light axion-like particle (ALP) via a quadratic coupling. Although the coupling is too feeble to thermalize the ALP, coherent forward scattering between the two sectors induces temperature-dependent mass shifts that substantially modify both WIMP freeze-out and ALP misalignment dynamics, giving rise to a novel coherent freeze-out mechanism. At high temperatures, the WIMP thermal bath spontaneously breaks the symmetry of the ALP potential, displacing the field to a new vacuum. The resulting back-reaction reduces the WIMP effective mass and significantly delays its freeze-out. Depending on the strength of the coupling, symmetry restoration occurs via either a first-order phase transition (FOPT) or a crossover. In the FOPT regime, dark matter consists solely of WIMPs, whose delayed freeze-out permits annihilation cross sections up to three orders of magnitude above the standard value, while still yielding the correct relic density. In the crossover regime, both WIMP and ALP can contribute to dark matter. Remarkably, we find an "ALP miracle": a Planck-suppressed quadratic coupling yields an ALP abundance comparable to the observed dark matter density, largely independent of its initial displacement and mass.
format Preprint
id arxiv_https___arxiv_org_abs_2511_16731
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle WIMP Meets ALP: Coherent Freeze-Out of Dark Matter
Ferrante, Steven
Perelstein, Maxim
Yu, Bingrong
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
We consider the cosmological history of a weakly interacting massive particle (WIMP) coupled to a light axion-like particle (ALP) via a quadratic coupling. Although the coupling is too feeble to thermalize the ALP, coherent forward scattering between the two sectors induces temperature-dependent mass shifts that substantially modify both WIMP freeze-out and ALP misalignment dynamics, giving rise to a novel coherent freeze-out mechanism. At high temperatures, the WIMP thermal bath spontaneously breaks the symmetry of the ALP potential, displacing the field to a new vacuum. The resulting back-reaction reduces the WIMP effective mass and significantly delays its freeze-out. Depending on the strength of the coupling, symmetry restoration occurs via either a first-order phase transition (FOPT) or a crossover. In the FOPT regime, dark matter consists solely of WIMPs, whose delayed freeze-out permits annihilation cross sections up to three orders of magnitude above the standard value, while still yielding the correct relic density. In the crossover regime, both WIMP and ALP can contribute to dark matter. Remarkably, we find an "ALP miracle": a Planck-suppressed quadratic coupling yields an ALP abundance comparable to the observed dark matter density, largely independent of its initial displacement and mass.
title WIMP Meets ALP: Coherent Freeze-Out of Dark Matter
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2511.16731