1,883 research outputs found
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 and at future Neutrino
Factories (NF, that exploit the \emph{golden} channels, i.e.
()) and Superbeam experiments (SB, that measure
the () 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
-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. (). 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 .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 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 , 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
Atmospheric neutrinos in ice and measurement of neutrino oscillation parameters
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 that the very high statistics
atmospheric neutrino data can be used to obtain precise measurements of the
main oscillation parameters.Comment: expanded discussion of systematic uncertainties, 8 pages, 4 figure
Souvenirs évoqués au contact avec la nature et leur relation avec l’identité et les préoccupations environnementales
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
Biases on cosmological parameters by general relativity effects
General relativistic corrections to the galaxy power spectrum appearing at
the horizon scale, if neglected, may induce biases on the measured values of
the cosmological parameters. In this paper, we study the impact of general
relativistic effects on non standard cosmologies such as scenarios with a time
dependent dark energy equation of state, with a coupling between the dark
energy and the dark matter fluids or with non-Gaussianities. We then explore
whether general relativistic corrections affect future constraints on
cosmological parameters in the case of a constant dark energy equation of state
and of non-Gaussianities. We find that relativistic corrections on the power
spectrum are not expected to affect the foreseen errors on the cosmological
parameters nor to induce large biases on them.Comment: 17 pages, 5 figures, one added figure, results of Tab. I revised,
version accepted for publication in PR
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