2022/12/20 by Liu, Ang, Shao, Feng-Lan, Han, Zhi-Long +2
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2212.10043
Provided the dark sector consisted of a dark scalar ϕ and a dark fermion χ under an exact Z2 symmetry, the sterile neutrino N can act as the messenger between the dark sector and standard model via the Yukawa coupling λds χϕN. In this paper, we focus on the specific scenario mN>mϕ+mχ with χ being a FIMP dark matter. The decay width of dark scalar ϕ is doubly suppressed by the smallness of Yukawa coupling λds and mixing angle θ. The delayed decay ϕ→χν will have a great impact on cosmological observables such as the Big Bang Nucleosynthesis, the Cosmic Microwave Background anisotropy power spectra, the effective number of relativistic neutrino species N\rm eff and the energetic neutrino flux. Meanwhile, the sterile neutrino can generate displaced vertex signature at colliders when mN