Puzzling out Neutrino Mixing Through Golden and Silver Measurements

We update a recent work devoted to resolve the degeneracies that appear in the simultaneous extraction of $\theta_{13}$ and $\delta$ at future Neutrino Factories (NF, that exploit the \emph{golden} channels, i.e. $\nu_e\to\nu_\mu$ ($\bar{\nu}_e\to\bar{\nu}_\mu$)) and Superbeam experiments (SB, that measure the $\nu_\mu\to\nu_e$ ($\bar{\nu}_\mu\to\bar{\nu}_e$) transitions). We consider the neutrino fluxes obtained with a new optics design for the CERN-SPL SB and assume the solar parameters within the LMA-I and the LMA-II regions indicated by recent KamLAND data. The dangerous fake solution associated with the $\theta_{23}$-ambiguity remains after the combination of data from these two facilities: in this perspective, we analyze the impact of the NF-\emph{silver} channels, i.e. $\nu_e\to\nu_\tau$ ($\bar{\nu}_e\to\bar{\nu}_\tau$). The combination of data from these three experiments -NF(\emph{golden} and \emph{silver} channels) plus SPL SB- can discover leptonic CP violation for values of $\theta_{13}\ge 1^{\circ}$.Comment: 6 pages, 8 figures. Presented at XXXVIII Rencontre De Moriond: Electroweak Interactions and Unified Theories Les Arcs, France, March 15--22, 200

Corrections to the fluxes of a Neutrino Factory

In view of their physics goals, future neutrino factories from muon decay aim at an overall flux precision of ${\cal O}(1$ or better. We analytically study the QED radiative corrections to the neutrino differential distributions from muon decay. Kinematic uncertainties due to the divergence of the muon beam are considered as well. The resulting corrections to the neutrino flux turn out to be of order ${\cal O}(0.1$, safely below the required precision.Comment: 22 pages, 8 figures. Some references changed. Final version accepted for publication in EPJ

Constraining inverse-curvature gravity with supernovae

We show that models of generalized modified gravity, with inverse powers of the curvature, can explain the current accelerated expansion of the Universe without resorting to dark energy and without conflicting with solar system experiments. We have solved the Friedmann equations for the full dynamical range of the evolution of the Universe and performed a detailed analysis of supernovae data in the context of such models that results in an excellent fit. If we further include constraints on the current expansion of the Universe and on its age, we obtain that the matter content of the Universe is 0.07 <=omega(m)<= 0.21 (95% C.L.). Hence the inverse-curvature gravity models considered cannot explain the dynamics of the Universe just with a baryonic matter component

Atmospheric neutrino oscillations and tau neutrinos in ice

The main goal of the IceCube Deep Core Array is to search for neutrinos of astrophysical origins. Atmospheric neutrinos are commonly considered as a background for these searches. We show here that cascade measurements in the Ice Cube Deep Core Array can provide strong evidence for tau neutrino appearance in atmospheric neutrino oscillations. A careful study of these tau neutrinos is crucial, since they constitute an irreducible background for astrophysical neutrino detection.Comment: 5 pages, 3 figure

On the improvement of the low energy neutrino factory

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, whilst 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_{e} -> nu_{mu} 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 theta13, 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 theta13 and delta for sin^{2}(2theta13) > 10^{-4} and to the mass hierarchy for sin^{2}(2theta13) > 10^{-3}.Comment: 13 pages, 8 eps figures. Version published in PRD - experimental section with preliminary results removed, abstract and conclusions re-written accordingly, title changed, author list amended

Cosmology-marginalized approaches in Bayesian model comparison: the neutrino mass as a case study

We propose here a \emph{novel} method which singles out the \emph{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.Comment: 6 pages, 1 table, 2 figures; matches version accepted for publication in PR

Summary of Golden Measurements at a ν\nu-Factory

The precision and discovery potential of a neutrino factory based on muon storage rings is summarized. For three-family neutrino oscillations, we analyze how to measure or severely constraint the angle $\theta_{13}$, CP violation, MSW effects and the sign of the atmospheric mass difference $\Delta m^2_{23}$. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500 km and 7332 km. We exploit the dependence of the signal on the neutrino energy, and include as well realistic background estimations and detection efficiencies. The optimal baseline turns out to be $O$(3000 km).Comment: 7 pages, Latex2e, 5 eps figures, use package espfi

Golden measurements at a neutrino factory

The precision and discovery potential of a neutrino factory based on muon storage rings is studied. For three-family neutrino oscillations, we analyse how to measure or severely constraint the angle $\theta_{13}$, CP violation, MSW effects and the sign of the atmospheric mass difference $\Delta m^2_{23}$. We present a simple analytical formula for the oscillation probabilities in matter, with all neutrino mass differences non-vanishing, which clarifies the subtleties involved in disentangling the unknown parameters. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500 km, and 7332 km. We exploit the dependence of the signal on the neutrino energy, and include as well realistic background estimations and detection efficiencies. The optimal baseline turns out to be ${\cal O}(3000$ km). Analyses combining the information from different baselines are also presented.Comment: 45 pages, Latex2e, 24 figures using epsfig.sty. An incorrect statement and a few misprints have been corrected. Results and conclusions are unchange