Pseudo-Dirac sterile neutrino dark matter
Abstract Sterile neutrino is a promising dark matter (DM) candidate. However, the parameter space of this scenario has almost been ruled out by the X-ray observation results whenever the sterile neutrino is solely produced by the Dodelson–Widrow (DW) mechanism in the early Universe. In this letter,...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-08-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-14546-7 |
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| Summary: | Abstract Sterile neutrino is a promising dark matter (DM) candidate. However, the parameter space of this scenario has almost been ruled out by the X-ray observation results whenever the sterile neutrino is solely produced by the Dodelson–Widrow (DW) mechanism in the early Universe. In this letter, we propose an extension to the minimal sterile neutrino DM model by introducing the pseudo-Dirac sterile neutrino, which implies the existence of two nearly degenerate Majorana states $${\hat{N}}_{1,2}^{\phantom{a}}$$ N ^ 1 , 2 a , and a permutation symmetry. The heavy state $${\hat{N}}_1$$ N ^ 1 is produced via the DW mechanism, and the light state $${\hat{N}}_2$$ N ^ 2 , which serves as the DM, is produced from the decay of $${\hat{N}}_1$$ N ^ 1 in the early Universe. The X-ray constraint is avoided by the permutation symmetry, which forbids the two-body decay of the DM into active neutrinos and photons. A promising signal of this scenario is the effective number of neutrino species, which will be precisely measured in future experiments, such as CMB stage IV. We further study the impact of this model on the cosmological parameters. The Markov Chain Monte Carlo analysis for the Planck + BAO + R19 data gives $$H_0=69.2_{-0.59}^{+0.58}$$ H 0 = 69 . 2 - 0.59 + 0.58 , which may relieve the Hubble tension. |
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| ISSN: | 1434-6052 |