Abstract: We propose here a novel method which singles out the a priori unavoidable dependence on the underlying cosmological model when extracting parameter constraints, providing robust limits which only depend on the considered dataset. Interestingly, when dealing with several possible cosmologies and interpreting the Bayesian preference in terms of the Gaussian statistical evidence, the preferred model is much less favored than when only two cases are compared. As a working example, we apply our approach to the cosmological neutrino mass bounds, which play a fundamental role not only in establishing the contribution of relic neutrinos to the dark matter of the Universe but also in the planning of future experimental searches of the neutrino character and of the neutrino mass ordering.

Abstract: The simplest models of inflation predict small non-Gaussianities and a featureless power spectrum. However, there exist a large number of well-motivated theoretical scenarios in which large non-Gaussianties could be generated. In general, in these scenarios the primordial power spectrum will deviate from its standard power law shape. We study, in a model-independent manner, the constraints from future large-scale structure surveys on the local non-Gaussianity parameter f(NL) when the standard power law assumption for the primordial power spectrum is relaxed. If the analyses are restricted to the large-scale-dependent bias induced in the linear matter power spectrum by non-Gaussianites, the errors on the f(NL) parameter could be increased by 60% when exploiting data from the future DESI survey, if dealing with only one possible dark matter tracer. In the same context, a nontrivial bias vertical bar delta f(NL)vertical bar similar to 2.5 could be induced if future data are fitted to the wrong primordial power spectrum. Combining all the possible DESI objects slightly ameliorates the problem, as the forecasted errors on f(NL) would be degraded by 40% when relaxing the assumptions concerning the primordial power spectrum shape. Also, the shift on the non-Gaussianity parameter is reduced in this case, vertical bar delta f(NL)vertical bar similar to 1.6. The addition of cosmic microwave background priors ensures robust future f(NL) bounds, as the forecasted errors obtained including these measurements are almost independent on the primordial power spectrum features, and vertical bar delta f(NL)vertical bar similar to 0.2, close to the standard single-field slow-roll paradigm prediction.

Abstract: We explore an extended cosmological scenario where the dark matter is an admixture of cold and additional noncold species. The mass and temperature of the noncold dark matter particles are extracted from a number of cosmological measurements. Among others, we consider tomographic weak lensing data and Milky Way dwarf satellite galaxy counts. We also study the potential of these scenarios in alleviating the existing tensions between local measurements and cosmic microwave background ( CMB) estimates of the S-8 parameter, with S-8 = sigma(8)root Omega(m), and of the Hubble constant H-0. In principle, a subdominant, noncold dark matter particle with a mass m(X) similar to keV, could achieve the goals above. However, the preferred ranges for its temperature and its mass are different when extracted from weak lensing observations and from Milky Way dwarf satellite galaxy counts, since these two measurements require suppressions of the matter power spectrum at different scales. Therefore, solving simultaneously the CMB-weak lensing tensions and the small scale crisis in the standard cold dark matter picture via only one noncold dark matter component seems to be challenging.

Abstract: We present a full Bayesian analysis of the combination of current neutrino oscillation, neutrinoless double beta decay and Cosmic Microwave Background observations. Our major goal is to carefully investigate the possibility to single out one neutrino mass ordering, namely Normal Ordering or Inverted Ordering, with current data. Two possible parametrizations (three neutrino masses versus the lightest neutrino mass plus the two oscillation mass splittings) and priors (linear versus logarithmic) are exhaustively examined. We find that the preference for NO is only driven by neutrino oscillation data. Moreover, the values of the Bayes factor indicate that the evidence for NO is strong only when the scan is performed over the three neutrino masses with logarithmic priors; for every other combination of parameterization and prior, the preference for NO is only weak. As a by-product of our Bayesian analyses, we are able to (a) compare the Bayesian bounds on the neutrino mixing parameters to those obtained by means of frequentist approaches, finding a very good agreement; (b) determine that the lightest neutrino mass plus the two mass splittings parametrization, motivated by the physical observables, is strongly preferred over the three neutrino mass eigenstates scan and (c) find that logarithmic priors guarantee a weakly-to-moderately more efficient sampling of the parameter space. These results establish the optimal strategy to successfully explore the neutrino parameter space, based on the use of the oscillation mass splittings and a logarithmic prior on the lightest neutrino mass, when combining neutrino oscillation data with cosmology and neutrinoless double beta decay. We also show that the limits on the total neutrino mass Sigma m(nu) can change dramatically when moving from one prior to the other. These results have profound implications for future studies on the neutrino mass ordering, as they crucially state the need for self-consistent analyses which explore the best parametrization and priors, without combining results that involve different assumptions.

Abstract: The low energy neutrino factory has been proposed as a very sensitive setup for future searches for CP violation and matter effects. Here we study how its performance is affected when the experimental specifications of the setup are varied. Most notably, we have considered the addition of the “platinum'' nu(mu) -> nu(e) channel. We find that, while theoretically the extra channel provides very useful complementary information and helps to lift degeneracies, its practical usefulness is lost when considering realistic background levels. Conversely, an increase in statistics in the ”golden'' nu(mu) -> nu(e) channel and, to some extent, an improvement in the energy resolution, lead to an important increase in the performance of the facility, given the rich energy dependence of the "golden'' channel at these energies. We show that a low energy neutrino factory with a baseline of 1300 km, muon energy of 4.5 GeV, and either a 20 kton totally active scintillating detector or 100 kton liquid argon detector, can have outstanding sensitivity to the neutrino oscillation parameters theta(13), delta, and the mass hierarchy. For our estimated exposure of 2: 8 x 10(23) kton x decays per muon polarity, the low energy neutrino factory has sensitivity to theta(13) and delta for sin(2)(2 theta(13)) > 10(-4) and to the mass hierarchy for sin(2)(2 theta(13)) > 10(-3)