172 research outputs found
Neutrino mass eigenstates and their ordering: a Bayesian approach
One of the not-yet determined properties of neutrinos is the ordering of
their mass eigenstates. We combine the available data from neutrino
oscillations, neutrinoless double beta decay and Cosmic Microwave Background
observations to derive robust constraints on the mass ordering in a Bayesian
context. Based on arxiv:1801.04946.Comment: 3 pages, 2 figures. To appear in the Proceedings of Incontri di
Fisica delle Alte Energie (IFAE) 201
Light sterile neutrinos and inflationary freedom
We perform a cosmological analysis in which we allow the primordial power spectrum of scalar perturbations to assume a shape that is different from the usual power-law predicted by the simplest models of cosmological inflation. We parameterize the free primordial power spectrum with a ``piecewise cubic Hermite interpolating polynomial'' (PCHIP). We consider a 3+1 neutrino mixing model with a sterile neutrino having a mass at the eV scale, which can explain the anomalies observed in short-baseline neutrino oscillation experiments. We find that the freedom of the primordial power spectrum allows to reconcile the cosmological data with a fully thermalized sterile neutrino in the early Universe. Moreover, the cosmological analysis gives us some information on the shape of the primordial power spectrum, which presents a feature around the wavenumber k=0.002 Mpc 121
Light Sterile Neutrinos and Inflationary Freedom
We perform a cosmological analysis in which we allow the primordial power
spectrum of scalar perturbations to assume a shape that is different from the
usual power-law predicted by the simplest models of cosmological inflation. We
parameterize the free primordial power spectrum with a "piecewise cubic Hermite
interpolating polynomial" (PCHIP). We consider a 3+1 neutrino mixing model with
a sterile neutrino having a mass at the eV scale, which can explain the
anomalies observed in short-baseline neutrino oscillation experiments. We find
that the freedom of the primordial power spectrum allows to reconcile the
cosmological data with a fully thermalized sterile neutrino in the early
Universe. Moreover, the cosmological analysis gives us some information on the
shape of the primordial power spectrum, which presents a feature around the
wavenumber .Comment: 19 pages; corrected Fig.4 and added Ref.[35
Light Sterile Neutrinos in Cosmology and Short-Baseline Oscillation Experiments
We analyze the most recent cosmological data, including Planck, taking into
account the possible existence of a sterile neutrino with a mass at the eV
scale indicated by short-baseline neutrino oscillations data in the 3+1
framework. We show that the contribution of local measurements of the Hubble
constant induces an increase of the value of the effective number of
relativistic degrees of freedom above the Standard Model value, giving an
indication in favor of the existence of sterile neutrinos and their
contribution to dark radiation. Furthermore, the measurements of the local
galaxy cluster mass distribution favor the existence of sterile neutrinos with
eV-scale masses, in agreement with short-baseline neutrino oscillations data.
In this case there is no tension between cosmological and short-baseline
neutrino oscillations data, but the contribution of the sterile neutrino to the
effective number of relativistic degrees of freedom is likely to be smaller
than one. Considering the Dodelson-Widrow and thermal models for the
statistical cosmological distribution of sterile neutrinos, we found that in
the Dodelson-Widrow model there is a slightly better compatibility between
cosmological and short-baseline neutrino oscillations data and the required
suppression of the production of sterile neutrinos in the early Universe is
slightly smaller.Comment: 12 pages; final version published in JHEP 1311 (2013) 21
Constraining power of open likelihoods, made prior-independent
One of the most criticized features of Bayesian statistics is the fact that
credible intervals, especially when open likelihoods are involved, may strongly
depend on the prior shape and range. Many analyses involving open likelihoods
are affected by the eternal dilemma of choosing between linear and logarithmic
prior, and in particular in the latter case the situation is worsened by the
dependence on the prior range under consideration. In this letter, we revive a
simple method to obtain constraints that depend neither on the prior shape nor
range and, using the tools of Bayesian model comparison, extend it to overcome
the possible dependence of the bounds on the choice of free parameters in the
numerical analysis. An application to the case of cosmological bounds on the
sum of the neutrino masses is discussed as an example.Comment: 6 pages, 3 figures; matches version accepted for publication in EPJ
Updated Global 3+1 Analysis of Short-BaseLine Neutrino Oscillations
We present the results of an updated fit of short-baseline neutrino
oscillation data in the framework of 3+1 active-sterile neutrino mixing. We
first consider and disappearance in the light of the
Gallium and reactor anomalies. We discuss the implications of the recent
measurement of the reactor spectrum in the NEOS experiment, which
shifts the allowed regions of the parameter space towards smaller values of
. The beta-decay constraints allow us to limit the oscillation
length between about 2 cm and 7 m at for neutrinos with an energy of
1 MeV. We then consider the global fit of the data in the light of the LSND
anomaly, taking into account the constraints from and
disappearance experiments, including the recent data of the MINOS and IceCube
experiments. The combination of the NEOS constraints on and the
MINOS and IceCube constraints on lead to an unacceptable
appearance-disappearance tension which becomes tolerable only in a pragmatic
fit which neglects the MiniBooNE low-energy anomaly. The minimization of the
global in the space of the four mixing parameters ,
, , and leads to three allowed
regions with narrow widths at (best-fit), 1.3 (at ), 2.4 (at ) eV. The
restrictions of the allowed regions of the mixing parameters with respect to
our previous global fits are mainly due to the NEOS constraints. We present a
comparison of the allowed regions of the mixing parameters with the
sensitivities of ongoing experiments, which show that it is likely that these
experiments will determine in a definitive way if the reactor, Gallium and LSND
anomalies are due to active-sterile neutrino oscillations or not.Comment: 39 pages; improved treatment of the reactor flux uncertainties and
other minor correction
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