1,790 research outputs found
Prediction of energy dissipation in violent sloshing flows simulated by Smoothed Particle Hydrodynamics
Prediction of energy dissipation in violent sloshing flows simulated by Smoothed Particle Hydrodynamic
Hints of theta_13>0 from global neutrino data analysis
Nailing down the unknown neutrino mixing angle theta_13 is one of the most
important goals in current lepton physics. In this context, we perform a global
analysis of neutrino oscillation data, focusing on theta_13, and including
recent results [Neutrino 2008, Proceedings of the XXIII International
Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand,
2008 (unpublished)]. We discuss two converging hints of theta_13>0, each at the
level of ~1sigma: an older one coming from atmospheric neutrino data, and a
newer one coming from the combination of solar and long-baseline reactor
neutrino data. Their combination provides the global estimate sin^2(theta_13) =
0.016 +- 0.010 (1sigma), implying a preference for \theta_13>0 with
non-negligible statistical significance (~90% C.L.). We discuss possible
refinements of the experimental data analyses, which might sharpen such
intriguing indication.Comment: Minor changes in the text. Matches published version in PR
Observables sensitive to absolute neutrino masses: A reappraisal after WMAP-3y and first MINOS results
In the light of recent neutrino oscillation and non-oscillation data, we
revisit the phenomenological constraints applicable to three observables
sensitive to absolute neutrino masses: The effective neutrino mass in single
beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless
double beta decay (m_2beta); and the sum of neutrino masses in cosmology
(Sigma). In particular, we include the constraints coming from the first Main
Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson
Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other
relevant cosmological data and priors. We find that the largest neutrino
squared mass difference is determined with a 15% accuracy (at 2-sigma) after
adding MINOS to world data. We also find upper bounds on the sum of neutrino
masses Sigma ranging from ~2 eV (WMAP-3y data only) to ~0.2 eV (all
cosmological data) at 2-sigma, in agreement with previous studies. In addition,
we discuss the connection of such bounds with those placed on the matter power
spectrum normalization parameter sigma_8. We show how the partial degeneracy
between Sigma and sigma_8 in WMAP-3y data is broken by adding further
cosmological data, and how the overall preference of such data for relatively
high values of sigma_8 pushes the upper bound of Sigma in the sub-eV range.
Finally, for various combination of data sets, we revisit the (in)compatibility
between current Sigma and m_2beta constraints (and claims), and derive
quantitative predictions for future single and double beta decay experiments.Comment: 18 pages, including 7 figure
Golden Ratio Prediction for Solar Neutrino Mixing
It has recently been speculated that the solar neutrino mixing angle is
connected to the golden ratio phi. Two such proposals have been made, cot
theta_{12} = phi and cos theta_{12} = phi/2. We compare these Ansatze and
discuss a model leading to cos theta_{12} = phi/2 based on the dihedral group
D_{10}. This symmetry is a natural candidate because the angle in the
expression cos theta_{12} = phi/2 is simply pi/5, or 36 degrees. This is the
exterior angle of a decagon and D_{10} is its rotational symmetry group. We
also estimate radiative corrections to the golden ratio predictions.Comment: 15 pages, 1 figure. Matches published versio
Observables sensitive to absolute neutrino masses: Constraints and correlations from world neutrino data
In the context of three-flavor neutrino mixing, we present a thorough study
of the phenomenological constraints applicable to three observables sensitive
to absolute neutrino masses: The effective neutrino mass in Tritium beta decay
(m_beta); the effective Majorana neutrino mass in neutrinoless double beta
decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). We
discuss the correlations among these variables which arise from the combination
of all the available neutrino oscillation data, in both normal and inverse
neutrino mass hierarchy. We set upper limits on m_beta by combining updated
results from the Mainz and Troitsk experiments. We also consider the latest
results on m_2beta from the Heidelberg-Moscow experiment, both with and without
the lower bound claimed by such experiment. We derive upper limits on Sigma
from an updated combination of data from the Wilkinson Microwave Anisotropy
Probe (WMAP) satellite and the 2 degrees Fields (2dF) Galaxy Redshifts Survey,
with and without Lyman-alpha forest data from the Sloan Digital Sky Survey
(SDSS), in models with a non-zero running of the spectral index of primordial
inflationary perturbations. The results are discussed in terms of
two-dimensional projections of the globally allowed region in the
(m_beta,m_2beta,Sigma) parameter space, which neatly show the relative impact
of each data set. In particular, the (in)compatibility between Sigma and
m_2beta constraints is highlighted for various combinations of data. We also
briefly discuss how future neutrino data (both oscillatory and non-oscillatory)
can further probe the currently allowed regions.Comment: 17 pages (RevTeX) + 7 figures (PostScript). Minor changes in text;
references added; results unchanged. To appear in PR
Probing non-standard decoherence effects with solar and KamLAND neutrinos
It has been speculated that quantum gravity might induce a "foamy" space-time
structure at small scales, randomly perturbing the propagation phases of
free-streaming particles (such as kaons, neutrons, or neutrinos). Particle
interferometry might then reveal non-standard decoherence effects, in addition
to standard ones (due to, e.g., finite source size and detector resolution.) In
this work we discuss the phenomenology of such non-standard effects in the
propagation of electron neutrinos in the Sun and in the long-baseline reactor
experiment KamLAND, which jointly provide us with the best available probes of
decoherence at neutrino energies E ~ few MeV. In the solar neutrino case, by
means of a perturbative approach, decoherence is shown to modify the standard
(adiabatic) propagation in matter through a calculable damping factor. By
assuming a power-law dependence of decoherence effects in the energy domain
(E^n with n = 0,+/-1,+/-2), theoretical predictions for two-family neutrino
mixing are compared with the data and discussed. We find that neither solar nor
KamLAND data show evidence in favor of non-standard decoherence effects, whose
characteristic parameter gamma_0 can thus be significantly constrained. In the
"Lorentz-invariant" case n=-1, we obtain the upper limit gamma_0<0.78 x 10^-26
GeV at 95% C.L. In the specific case n=-2, the constraints can also be
interpreted as bounds on possible matter density fluctuations in the Sun, which
we improve by a factor of ~ 2 with respect to previous analyses.Comment: Minor changes. Version accepted for publication in Phys. Rev.
Bridging the knowledge gap on the distribution and typology of vermetid bioconstructions along the Maltese coastline: an updated assessment
In the Maltese Islands, insufficient attention has been paid to vermetid reefs, endemic Mediterranean bioconstructions widely distributed along the southern part of the basin. As a result, this is a largely-overlooked coastal ecosystem despite the multitude of ecosystem services it provides. The perennial urban development in the Maltese Islands calls for the adoption of urgent action to protect coastal habitats, in particular bioconstructions that increase biodiversity and contribute to mitigating the effects of climate change. The objective of our study was to extensively document the presence and typology of the vermetid reef ecosystems along the coast of Malta and Gozo, assessing the occurrence of putative anthropogenic threats on the same ecosystem. Quantitative measurements were additionally taken to morphologically characterize the recorded bioconstructions. Furthermore, we tested the human pressure effect on the density of vermetid individuals and associated biodiversity. “True” trottoirs were only documented along the south-east coast of Malta, where unfortunately land reclamation projects are expected to be implemented. Although no direct relation between a number of assessed human activities and the density of vermetid individuals was reported in the current study, we suggest the conduction of further studies to investigate the influence of specific disturbances on the conservation status of this ecosystem. This study expands the existing knowledge on the status of vermetid reefs in the Maltese Islands and calls for management and conservation actions to preserve this bioconstruction
The first confirmed record of the Atlantic blue crab Callinectes sapidus Rathbun, 1896 (Decapoda, Brachyura) from Maltese waters
The invasive portunid species Callinectes sapidus is hereby recorded for the first time from Maltese waters, thus updating the known distribution of this decapod of Atlantic origin within the Mediterranean. Potential introduction pathways of the species to Maltese waters are discussed
Where we are on : addendum to "Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters"
In this addendum to arXiv:1103.0734 we consider the recent results from
long-baseline searches at the T2K and MINOS experiments and
investigate their implications for the mixing angle and the
leptonic Dirac CP phase . By combining the indication for a
non-zero value of coming from T2K data with global neutrino
oscillation data we obtain a significance for of about
with best fit points for normal
(inverted) neutrino mass ordering. These results depend somewhat on assumptions
concerning the analysis of reactor neutrino data.Comment: 5 pages, 2 figures and 1 tabl
- …