http://arxiv.org/abs/1405.4670
We propose a scenario in which extra light fermions in an $E_6$-inspired U(1) extension of the standard model constitute the dark matter, as a simple variation of our model for dark radiation presented in 2010. Interestingly, for the light fermions of mass about 7 keV, they radiatively decay into active neutrinos and photons with a lifetime in the range of $10^{27}-10^{28}$ seconds, which naturally explains the recently discovered 3.5 keV X-ray line signal.
K. Nakayama, F. Takahashi and T. Yanagida
Tue, 20 May 14
41/62
Comments: 7 pages
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