Abstract: Inflation predicts primordial scalar perturbations with a nearly scale-invariant spectrum and a spectral index approximately unity [the Harrison-Zel'dovich (HZ) spectrum]. The first important step for inflationary cosmology is to check the consistency of the HZ primordial spectrum with current observations. Recent analyses have claimed that a HZ primordial spectrum is excluded at more than 99% c. l. Here we show that the HZ spectrum is only marginally disfavored if one considers a more general reionization scenario. Data from the Planck mission will settle the issue.

Abstract: Determination of whether the Harrison-Zel'dovich spectrum for primordial scalar perturbations is consistent with observations is sensitive to assumptions about the reionization scenario. In light of this result, we revisit constraints on inflationary models using more general reionization scenarios. While the bounds on the tensor-to-scalar ratio are largely unmodified, when different reionization schemes are addressed, hybrid models are back into the inflationary game. In the general reionization picture, we reconstruct both the shape and amplitude of the inflaton potential. We discuss how relaxing the simple reionization restriction affects the reconstruction of the potential through the changes in the constraints on the spectral index, the tensor-to-scalar ratio and the running of the spectral index. We also find that the inclusion of other Cosmic Microwave Background data in addition to the Wilkinson Microwave Anisotropy probe data excludes the very flat potentials typical of models in which the inflationary evolution reaches a late-time attractor, as a consequence of the fact that the running of the spectral index is constrained to be different from zero at 99% confidence level.

Abstract: Cosmological constraints on the sum of neutrino masses and on the effective number of neutrino species in standard and nonstandard scenarios are computed using the most recent available cosmological data. Our cosmological data sets include the measurement of the baryonic acoustic oscillation (BAO) feature in the data release 9 CMASS sample of the baryon oscillation spectroscopic survey. We study in detail the different degeneracies among the parameters, as well as the impact of the different data sets used in the analyses. When considering bounds on the sum of the three active neutrino masses, the information in the BAO signal from galaxy clustering measurements is approximately equally powerful as the shape information from the matter power spectrum. The most stringent bound we find is Sigma m(nu) < 0.32 eV at 95% C.L. When nonstandard neutrino scenarios with N-eff massless or massive neutrino species are examined, power spectrum shape measurements provide slightly better bounds than the BAO signal only, due to the breaking of parameter degeneracies. Cosmic microwave background data from high multipoles from the South Pole Telescope turns out to be crucial for extracting the number of effective neutrino species. Recent baryon oscillation spectroscopic survey data combined with cosmic microwave background and Hubble Space Telescope measurements give N-eff = 3.66(-0.21-0.69)(+0.20+0.73) in the massless neutrino scenario, and similar results are obtained in the massive case. The evidence for extra radiation N-eff > 3 often claimed in the literature therefore remains at the 2 sigma level when considering up-to-date cosmological data sets. Measurements from the Wilkinson Microwave Anisotropy Probe combined with a prior on the Hubble parameter from the Hubble Space Telescope are very powerful in constraining either the sum of the three active neutrino masses or the number of massless neutrino species. If the former two parameters are allowed to freely vary, however, the bounds from the combination of these two cosmological probes get worse by an order of magnitude.