Dark matter and dark radiation from chiral $U(1)$ gauge symmetry

Fuente: arXiv
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Hauptverfasser: He, Xiao, Nomura, Takaaki, Yokozaki, Norimi
Format: Preprint
Veröffentlicht: 2025
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author He, Xiao
Nomura, Takaaki
Yokozaki, Norimi
author_facet He, Xiao
Nomura, Takaaki
Yokozaki, Norimi
contents We consider a simple model of a dark sector with a chiral $U(1)$ gauge symmetry. The anomaly-free condition requires at least five chiral fermions. Some of the fermions acquire masses through a vacuum expectation value of a Higgs field, and they are stable due to an accidental symmetry. This makes them dark matter candidates. If the dark sector was once in thermal equilibrium with the Standard Model and dark radiation constraints are included, two-component dark matter may be needed since the number of massless fermions is restricted. When the Dirac fermion is the main component of dark matter, the kinetic mixing should be around $10^{-6}$: a larger value is restricted by direct detection limits, while a smaller value prevents thermal freeze-out. If the main dark matter component is a Majorana fermion, the kinetic mixing can be larger. Still, a sub-component of Dirac fermion could produce a detectable signal in future direct detection experiments. We also discuss the possibility of testing an invisible dark photon at future lepton collider experiments, taking into account cosmological constraints.
format Preprint
id arxiv_https___arxiv_org_abs_2506_04718
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dark matter and dark radiation from chiral $U(1)$ gauge symmetry
He, Xiao
Nomura, Takaaki
Yokozaki, Norimi
High Energy Physics - Phenomenology
High Energy Physics - Experiment
We consider a simple model of a dark sector with a chiral $U(1)$ gauge symmetry. The anomaly-free condition requires at least five chiral fermions. Some of the fermions acquire masses through a vacuum expectation value of a Higgs field, and they are stable due to an accidental symmetry. This makes them dark matter candidates. If the dark sector was once in thermal equilibrium with the Standard Model and dark radiation constraints are included, two-component dark matter may be needed since the number of massless fermions is restricted. When the Dirac fermion is the main component of dark matter, the kinetic mixing should be around $10^{-6}$: a larger value is restricted by direct detection limits, while a smaller value prevents thermal freeze-out. If the main dark matter component is a Majorana fermion, the kinetic mixing can be larger. Still, a sub-component of Dirac fermion could produce a detectable signal in future direct detection experiments. We also discuss the possibility of testing an invisible dark photon at future lepton collider experiments, taking into account cosmological constraints.
title Dark matter and dark radiation from chiral $U(1)$ gauge symmetry
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2506.04718