64,020 research outputs found
Mass problem in the Standard Model
We propose a new gauge model which is non universal
respect to the three fermion families of the Standard Model. We introduce
additional one top-like quark, two bottom-like quarks and three right handed
neutrinos in order to have an anomaly free theory. We also consider additional
three right handed neutrinos which are singlets respect to the gauge symmetry
of the model to implement see saw mechanism and give masses to the light
neutrinos according to the neutrino oscillation phenomenology. In the context
of this horizontal gauge symmetry we find mass ansatz for leptons and quarks.
In particular, from the analysis of solar, atmospheric, reactor and accelerator
neutrino oscillation experiments, we get the allow region for the Yukawa
couplings for the charge and neutral lepton sectors according with the mass
squared differences and mixing angles for the two neutrino hierarchy schemes,
normal and inverted.Comment: Conference proceedings from 6th International Conference on New
Frontiers in Physics (ICNFP 2017) from August 17th to 29th of 2017 at the
Conference Center of the Orthodox Academy of Creta (OAC) in Kolymbari
(Crete), Greec
Aeroacoustic theory for noncompact wing-gust interaction
Three aeroacoustic models for noncompact wing-gust interaction were developed for subsonic flow. The first is that for a two dimensional (infinite span) wing passing through an oblique gust. The unsteady pressure field was obtained by the Wiener-Hopf technique; the airfoil loading and the associated acoustic field were calculated, respectively, by allowing the field point down on the airfoil surface, or by letting it go to infinity. The second model is a simple spanwise superposition of two dimensional solutions to account for three dimensional acoustic effects of wing rotation (for a helicopter blade, or some other rotating planform) and of finiteness of wing span. A three dimensional theory for a single gust was applied to calculate the acoustic signature in closed form due to blade vortex interaction in helicopters. The third model is that of a quarter infinite plate with side edge through a gust at high subsonic speed. An approximate solution for the three dimensional loading and the associated three dimensional acoustic field in closed form was obtained. The results reflected the acoustic effect of satisfying the correct loading condition at the side edge
Adsorbate surface diffusion: The role of incoherent tunneling in light particle motion
The role of incoherent tunneling in the diffusion of light atoms on surfaces
is investigated. With this purpose, a Chudley-Elliot master equation
constrained to nearest neighbors is considered within the Grabert-Weiss
approach to quantum diffusion in periodic lattices. This model is applied to
recent measurements of atomic H and D on Pt(111), rendering friction
coefficients that are in the range of those available in the literature for
other species of adsorbates. A simple extension of the model has also been
considered to evaluate the relationship between coverage and tunneling, and
therefore the feasibility of the approach. An increase of the tunneling rate
has been observed as the surface coverage decreases.Comment: 7 pages, 2 figures; important reorganization of the work (including
title changes
Phonon lineshapes in atom-surface scattering
Phonon lineshapes in atom-surface scattering are obtained from a simple
stochastic model based on the so-called Caldeira-Leggett Hamiltonian. In this
single-bath model, the excited phonon resulting from a creation or annihilation
event is coupled to a thermal bath consisting of an infinite number of harmonic
oscillators, namely the bath phonons. The diagonalization of the corresponding
Hamiltonian leads to a renormalization of the phonon frequencies in terms of
the phonon friction or damping coefficient. Moreover, when there are adsorbates
on the surface, this single-bath model can be extended to a two-bath model
accounting for the effect induced by the adsorbates on the phonon lineshapes as
well as their corresponding lineshapes.Comment: 14 pages, 2 figure
A data assimilation algorithm for the subcritical surface quasi-geostrophic equation
In this article, we prove that data assimilation by feedback nudging can be
achieved for the three-dimensional quasi-geostrophic equation in a simplified
scenario using only large spatial scale observables on the dynamical boundary.
On this boundary, a scalar unknown (buoyancy or surface temperature of the
fluid) satisfies the surface quasi-geostrophic equation. The feedback nudging
is done on this two-dimensional model, yet ultimately synchronizes the
streamfunction of the three-dimensional flow. The main analytical difficulties
are due to the presence of a nonlocal dissipative operator in the surface
quasi-geostrophic equation. This is overcome by exploiting a suitable partition
of unity, the modulus of continuity characterization of Sobolev space norms,
and the Littlewood-Paley decomposition to ultimately establish various
boundedness and approximation-of-identity properties for the observation
operators.Comment: 28 pages, referee comments incorporated, references added, abstract
and introduction modified, main theorems cover full subcritical range of
dissipation, certain boundedness properties of observation operators extende
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