Is there evidence for additional neutrino species from cosmology?

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It has been suggested that recent cosmological and
flavor-oscillation data favor the existence of additional neutrino species
beyond the three standard flavors. We apply Bayesian model selection to
determine whether there is any evidence from current cosmological datasets for
the standard cosmological model to be extended to include additional neutrino
flavors. The datasets employed include cosmic microwave background temperature,
polarization and lensing data, and measurements of the baryon acoustic
oscillation scale and the Hubble constant. We also consider other additional
neutrino physics, such as massive neutrinos, and possible degeneracies with
other cosmological parameters.