Ultralight dark matter from non-slowroll inflation

Fuente: arXiv
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Main Authors: La Rosa, Martina, Tasinato, Gianmassimo
Format: Preprint
Published: 2025
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author La Rosa, Martina
Tasinato, Gianmassimo
author_facet La Rosa, Martina
Tasinato, Gianmassimo
contents The longitudinal mode of a massive vector field, generated during inflation, offers a well-motivated and phenomenologically rich candidate for dark matter. We show that a rapid variation in the mass of the vector boson, occurring during a brief phase of non-slowroll inflationary evolution, can naturally give rise to extremely small vector masses after inflation ends, corresponding to an ultralight dark matter candidate. This mechanism predicts a stochastic gravitational-wave background, generated at second order by non-adiabatic longitudinal vector fluctuations and amplified at very low frequencies, yielding a distinctive observational signature of the scenario. By leveraging a brief departure from slowroll dynamics during inflation - commonly invoked in scenarios that produce primordial black holes - our framework establishes a novel connection between ultralight vector dark matter and primordial black hole physics, suggesting a possible unified setting for mixed dark matter scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2508_16455
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ultralight dark matter from non-slowroll inflation
La Rosa, Martina
Tasinato, Gianmassimo
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
The longitudinal mode of a massive vector field, generated during inflation, offers a well-motivated and phenomenologically rich candidate for dark matter. We show that a rapid variation in the mass of the vector boson, occurring during a brief phase of non-slowroll inflationary evolution, can naturally give rise to extremely small vector masses after inflation ends, corresponding to an ultralight dark matter candidate. This mechanism predicts a stochastic gravitational-wave background, generated at second order by non-adiabatic longitudinal vector fluctuations and amplified at very low frequencies, yielding a distinctive observational signature of the scenario. By leveraging a brief departure from slowroll dynamics during inflation - commonly invoked in scenarios that produce primordial black holes - our framework establishes a novel connection between ultralight vector dark matter and primordial black hole physics, suggesting a possible unified setting for mixed dark matter scenarios.
title Ultralight dark matter from non-slowroll inflation
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
url https://arxiv.org/abs/2508.16455