Z′ Portal Dark Matter with Observable ΔNeff
Abstract
In the conventional Z′ portal dark matter scenario, the prediction of detectable dark matter χ typically relies on the collider sensitivities of Z′ and direct detection, where the Majorana type right-handed neutrinos are usually assumed. However, if the right-handed neutrinos νR are Dirac type, they will contribute to the additional effective number of relativistic species ΔNeff, which brings different detectable predictions for Z′ portal dark matter. In light of the great improvement of ΔNeff for the upcoming experiments, we investigate the Z′ portal dark matter with Dirac type νR. Under the U(1)B−L symmetry, this model includes νR with U(1)B−L charge QνR=−1 and χ with arbitrary Qχ beyond the SM. Based on the relation in the production of χ and νR, both the WIMP and FIMP dark matter through the Z′ portal scenario are considered. We perform a comprehensive exploration of the viable parameter space under the constraints from ΔNeff induced by thermal and non-thermal νR, perturbative limit, dark matter direct and indirect detection, and collider searches of Z′.
Related
BibTeX
@misc{liu2026portal,
title = {{$Z^\prime$ Portal Dark Matter with Observable $ΔN_\rm eff$}},
author = {Ang Liu and Zhi-Long Han and Fei Huang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.08082},
eprint = {2607.08082},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.08082},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Z^′ Portal Dark Matter with Observable ΔN_eff
AU - Ang Liu
AU - Zhi-Long Han
AU - Fei Huang
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2607.08082
UR - https://arxiv.org/abs/2607.08082
AB - In the conventional Z^′ portal dark matter scenario, the prediction of detectable dark matter χ typically relies on the collider sensitivities of Z^′ and direct detection, where the Majorana type right-handed neutrinos are usually assumed. However, if the right-handed neutrinos ν_R are Dirac type, they will contribute to the additional effective number of relativistic species ΔN_eff, which brings different detectable predictions for Z^′ portal dark matter. In light of the great improvement of ΔN_eff for the upcoming experiments, we investigate the Z^′ portal dark matter with Dirac type ν_R. Under the U(1)_B−L symmetry, this model includes ν_R with U(1)_B−L charge Q_ν_R=−1 and χ with arbitrary Q_χ beyond the SM. Based on the relation in the production of χ and ν_R, both the WIMP and FIMP dark matter through the Z^′ portal scenario are considered. We perform a comprehensive exploration of the viable parameter space under the constraints from ΔN_eff induced by thermal and non-thermal ν_R, perturbative limit, dark matter direct and indirect detection, and collider searches of Z^′.
ER -