Abstract: We present a novel approach to derive constraints on neutrino masses, as well as on other cosmological parameters, from cosmological data, while taking into account our ignorance of the neutrino mass ordering. We derive constraints from a combination of current as well as future cosmological datasets on the total neutrino mass M-nu and on the mass fractions f(nu),i = m(i)/M-nu (where the index i = 1, 2, 3 indicates the three mass eigenstates) carried by each of the mass eigenstates m(i), after marginalizing over the (unknown) neutrino mass ordering, either normal ordering (NH) or inverted ordering (IH). The bounds on all the cosmological parameters, including those on the total neutrino mass, take therefore into account the uncertainty related to our ignorance of the mass hierarchy that is actually realized in nature. This novel approach is carried out in the framework of Bayesian analysis of a typical hierarchical problem, where the distribution of the parameters of the model depends on further parameters, the hyperparameters. In this context, the choice of the neutrino mass ordering is modeled via the discrete hyperparameter h(type), which we introduce in the usual Markov chain analysis. The preference from cosmological data for either the NH or the IH scenarios is then simply encoded in the posterior distribution of the hyper-parameter itself. Current cosmic microwave background (CMB) measurements assign equal odds to the two hierarchies, and are thus unable to distinguish between them. However, after the addition of baryon acoustic oscillation (BAO) measurements, a weak preference for the normal hierarchical scenario appears, with odds of 4 : 3 from Planck temperature and large-scale polarization in combination with BAO (3 : 2 if small-scale polarization is also included). Concerning next-generation cosmological experiments, forecasts suggest that the combination of upcoming CMB (COrE) and BAO surveys (DESI) may determine the neutrino mass hierarchy at a high statistical significance if the mass is very close to the minimal value allowed by oscillation experiments, as for NH and a fiducial value of M-nu = 0.06 eV there is a 9 : 1 preference of normal versus inverted hierarchy. On the contrary, if the sum of the masses is of the order of 0.1 eV or larger, even future cosmological observations will be inconclusive. The innovative statistical strategy exploited here represents a very simple, efficient and robust tool to study the sensitivity of present and future cosmological data to the neutrino mass hierarchy, and a sound competitor to the standard Bayesian model comparison. The unbiased limit on M-nu we obtain is crucial for ongoing and planned neutrinoless double beta decay searches.

Abstract: We perform calculations for the eta(c) -> eta pi(+)pi(-) decay using elements of SU(3) symmetry to see the weight of different trios of pseudoscalars produced in this decay, prior to the final state interaction of the mesons. After that, the interaction of pairs of mesons, leading finally to eta pi(+)pi(-), is done using the chiral unitary approach. We evaluate the pi(+)pi(-) and pi eta mass distributions and find large and clear signals for f(0)(500), f(0)(980) and a(0)(980) excitation. The reaction is similar to the chi(c1) -> eta pi(+)pi(-), which has been recently measured at BESIII and its implementation and comparison with these predictions will be very valuable to shed light on the nature of the low mass scalar mesons.

Abstract: We study the strange vector meson (K*, (K) over bar*) dynamics in relativistic heavy-ion collisions based on the microscopic parton-hadron-string dynamics (PHSD) transport approach which incorporates partonic and hadronic degrees of freedom, a phase transition from hadronic to partonic matter-quark-gluon-plasma (QGP)-and a dynamical hadronization of quarks and antiquarks as well as final hadronic interactions. We investigate the role of in-medium effects on the K*, (K) over bar* meson dynamics by employing Breit-Wigner spectral functions for the K* with self-energies obtained from a self-consistent coupled-channelG-matrix approach. Furthermore, we confront the PHSD calculations with experimental data for p + p, Cu + Cu, and Au + Au collisions at energies up to root s(NN) = 200 GeV. Our analysis shows that, at relativistic energies, most of the final K* (observed experimentally) are produced during the late hadronic phase, dominantly by the K + pi -> K* channel, such that the fraction of the K* from the QGP is small and can hardly be reconstructed from the final observables. The influence of the in-medium effects on the K* dynamics at energies typical of the BNL Relativistic Heavy Ion Collider is rather modest due to their dominant production at low baryon densities (but high meson densities); however, it increases with decreasing beam energy. Moreover, we find that the additional cut on the invariant-mass region of the K* further influences the shape and the height of the final spectra. This imposes severe constraints on the interpretation of the experimental results.