Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8187993 | Physics Letters B | 2013 | 5 Pages |
Abstract
We consider a simple class of models where dark radiation has self-interactions and therefore does not free stream. Such dark radiation has no anisotropic stress (or viscosity), leaving a distinct signature on the CMB angular power spectrum. Specifically we study a possibility that hidden gauge bosons and/or chiral fermions account for the excess of the effective number of neutrino species. They have gauge interactions and remain light due to the unbroken hidden gauge symmetry, leading to ÎNeffâ0.29 in some case.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Nuclear and High Energy Physics
Authors
Kwang Sik Jeong, Fuminobu Takahashi,