Mirror dark matter cosmology - predictions for $N_{eff} [CMB]$ and $N_{eff} [BBN]$

Mirror dark matter interacting with ordinary matter via photon-mirror photon kinetic mixing can explain the DAMA, CoGeNT and CRESSTII direct detection experiments. This explanation requires kinetic mixing of strength $ε\sim 10^{-9}$. Such kinetic mixing will have important implications for early Universe cosmology. We calculate the additional relativistic energy density at recombination, $δN_{eff} [CMB]$. We also calculate the effects for big bang nucleosynthesis, $δN_{eff} [BBN]$. Current hints that both $δN_{eff} [CMB]$ and $δN_{eff} [BBN]$ are non-zero and positive can be accommodated within this framework if $ε\approx few \times 10^{-9}$. In the near future, measurements from the Planck mission will either confirm these hints or constrain $ε\stackrel{<}{\sim} 10^{-9}$.

No reviews yet.

No comments yet.