45,011 research outputs found
Neutrino masses and mixing in A4 models with three Higgs doublets
We study neutrino masses and mixing in the context of flavor models with A4
symmetry, three scalar doublets in the triplet representation, and three lepton
families. We show that there is no representation assignment that yields a
dimension-five mass operator consistent with experiment. We then consider a
type-I seesaw with three heavy right-handed neutrinos, explaining in detail why
it fails, and showing with a numerical example that agreement with the present
neutrino oscillation data can be recovered with the inclusion of
dimension-three heavy neutrino mass terms that break softly the A4 symmetry.Comment: 10 pages, RevTex, 3 figures. v2: much expanded section on softly
broken A4; refs adde
The impact of a wave farm on large scale sediment transport
This study investigates the interactions of waves and tides at a wave farm in the southwest of England, in particular their effects on radiation stress, bottom stress, and consequently on the sediment transport and the coast adjacent to the wave-farm (the Wave Hub). In this study, an integrated complex numerical modelling system is setup at the Wave Hub site and is used to compute the wave and current fields by taking into account the wave-current interaction, as well as the sediment transport. Results show that tidal elevation and tidal currents have a significant effect on the wave height and direction predictions; tidal forcing and wind waves have a significant effect on the bed shear-stress, relevant to sediment transport; waves via radiation stresses have an important effect on the longshore and cross-shore velocity components, particularly during the spring tides. Waves can impact on bottom boundary layer and mixing in the water column. The results highlight the importance of the interactions between waves and tides when modelling coastal morphology with presence of wave energy devices
A linear filter to reconstruct the ISW effect from CMB and LSS observations
The extraction of a signal from some observational data sets that contain
different contaminant emissions, often at a greater level than the signal
itself, is a common problem in Astrophysics and Cosmology. The signal can be
recovered, for instance, using a simple Wiener filter. However, in certain
cases, additional information may also be available, such as a second
observation which correlates to a certain level with the sought signal. In
order to improve the quality of the reconstruction, it would be useful to
include as well this additional information. Under these circumstances, we have
constructed a linear filter, the linear covariance-based filter, that extracts
the signal from the data but takes also into account the correlation with the
second observation. To illustrate the performance of the method, we present a
simple application to reconstruct the so-called Integrated Sachs-Wolfe effect
from simulated observations of the Cosmic Microwave Background and of
catalogues of galaxies.Comment: 8 pages, 6 figures, accepted for publication in the IEEE Journal of
Selected Topics in Signal Processin
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