Sub-GeV dark matter and nano-Hertz gravitational waves from a classically conformal dark sector

Fuente: arXiv
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Autores principales: Balan, Sowmiya, Bringmann, Torsten, Kahlhoefer, Felix, Matuszak, Jonas, Tasillo, Carlo
Formato: Preprint
Publicado: 2025
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author Balan, Sowmiya
Bringmann, Torsten
Kahlhoefer, Felix
Matuszak, Jonas
Tasillo, Carlo
author_facet Balan, Sowmiya
Bringmann, Torsten
Kahlhoefer, Felix
Matuszak, Jonas
Tasillo, Carlo
contents Strong first-order phase transitions in a dark sector offer a compelling explanation for the stochastic gravitational wave background in the nano-Hertz range recently detected by pulsar timing arrays (PTAs). We explore the possibility that such a phase transition at the same time gives mass to a stable fermion that accounts for the observed dark matter abundance and leads to testable effects in laboratory experiments. Concretely, we consider a classically conformal dark sector with a hidden $U(1)^\prime$ gauge symmetry that couples to the Standard Model via kinetic mixing. Since the PTA signal requires a phase transition in the MeV temperature range, spontaneous symmetry breaking gives rise to a sub-GeV dark matter candidate that couples to the Standard Model via a dark photon mediator and obtains its relic abundance via annihilations into electrons and dark Higgs bosons. Such a scenario is tightly constrained by laboratory searches for dark photons and cosmological constraints on the decays of dark Higgs bosons after the phase transition. We show that viable parameter regions can be found both for the case that the dark Higgs bosons remain in equilibrium with the Standard Model and that they decouple and only decay much later. In the latter case, the parameter regions preferred by the PTA signal and the dark matter relic abundance can be fully explored by future beam-dump experiments searching for missing energy.
format Preprint
id arxiv_https___arxiv_org_abs_2502_19478
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sub-GeV dark matter and nano-Hertz gravitational waves from a classically conformal dark sector
Balan, Sowmiya
Bringmann, Torsten
Kahlhoefer, Felix
Matuszak, Jonas
Tasillo, Carlo
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
Strong first-order phase transitions in a dark sector offer a compelling explanation for the stochastic gravitational wave background in the nano-Hertz range recently detected by pulsar timing arrays (PTAs). We explore the possibility that such a phase transition at the same time gives mass to a stable fermion that accounts for the observed dark matter abundance and leads to testable effects in laboratory experiments. Concretely, we consider a classically conformal dark sector with a hidden $U(1)^\prime$ gauge symmetry that couples to the Standard Model via kinetic mixing. Since the PTA signal requires a phase transition in the MeV temperature range, spontaneous symmetry breaking gives rise to a sub-GeV dark matter candidate that couples to the Standard Model via a dark photon mediator and obtains its relic abundance via annihilations into electrons and dark Higgs bosons. Such a scenario is tightly constrained by laboratory searches for dark photons and cosmological constraints on the decays of dark Higgs bosons after the phase transition. We show that viable parameter regions can be found both for the case that the dark Higgs bosons remain in equilibrium with the Standard Model and that they decouple and only decay much later. In the latter case, the parameter regions preferred by the PTA signal and the dark matter relic abundance can be fully explored by future beam-dump experiments searching for missing energy.
title Sub-GeV dark matter and nano-Hertz gravitational waves from a classically conformal dark sector
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2502.19478