32,493 research outputs found
Fast-to-Alfv\'en mode conversion mediated by Hall current. II Application to the solar atmosphere
Coupling between fast magneto-acoustic and Alfv\'en waves can be observe in
fully ionized plasmas mediated by stratification and 3D geometrical effects. In
Paper I, Cally & Khomenko (2015) have shown that in a weakly ionized plasma,
such as the solar photosphere and chromosphere, the Hall current introduces a
new coupling mechanism. The present study extends the results from Paper I to
the case of warm plasma. We report on numerical experiments where mode
transformation is studied using quasi-realistic stratification in thermodynamic
parameters resembling the solar atmosphere. This redresses the limitation of
the cold plasma approximation assumed in Paper I, in particular allowing the
complete process of coupling between fast and slow magneto-acoustic modes and
subsequent coupling of the fast mode to the Alfv\'en mode through the Hall
current. Our results confirm the efficacy of the mechanism proposed in Paper I
for the solar case. We observe that the efficiency of the transformation is a
sensitive function of the angle between the wave propagation direction and the
magnetic field, and of the wave frequency. The efficiency increases when the
field direction and the wave direction are aligned for increasing wave
frequencies. After scaling our results to typical solar values, the maximum
amplitude of the transformed Alfv\'en waves, for a frequency of 1 Hz,
corresponds to an energy flux (measured above the height of peak Hall coupling)
of , based on an amplitude of 500 at
, which is sufficient to play a major role in both quiet and active
region coronal heating
Strong Pionic Decays From a Spectroscopic Quark Model
From a refined non-relativistic quark model that fits the baryonic low-energy
spectrum the study of strong pion decay processes within an elementary emission
model scheme points out the need of incorporating size-contributing components
into the baryon wave functions. In particular the effect of a (qqq qantiq)
component is investigated in the framework of a quark pair creation model.Comment: 26 pages, 9 figures (1 postscript file), LaTe
Combined analysis of the decays and
In a combined study of the decay spectra of and
decays within a dispersive representation of the
required form factors, we illustrate how the resonance parameters,
defined through the pole position in the complex plane, can be extracted with
improved precision as compared to previous studies. While we obtain a
substantial improvement in the mass, the uncertainty in the width is only
slightly reduced, with the findings MeV and
MeV. Further constraints on the width
could result from updated analyses of the and/or spectra using
the full Belle-I data sample. Prospects for Belle-II are also discussed. As the
vector form factor enters the description of the decay , we are in a position to investigate isospin violations in its
parameters like the form factor slopes. In this respect also making available
the spectrum of the transition would be extremely
useful, as it would allow to study those isospin violations with much higher
precision.Comment: 20 pages, 1figur
Suspensions Thermal Noise in the LIGO Gravitational Wave Detector
We present a calculation of the maximum sensitivity achievable by the LIGO
Gravitational wave detector in construction, due to limiting thermal noise of
its suspensions. We present a method to calculate thermal noise that allows the
prediction of the suspension thermal noise in all its 6 degrees of freedom,
from the energy dissipation due to the elasticity of the suspension wires. We
show how this approach encompasses and explains previous ways to approximate
the thermal noise limit in gravitational waver detectors. We show how this
approach can be extended to more complicated suspensions to be used in future
LIGO detectors.Comment: 28 pages, 13 figure
Marginal Fermi liquid behavior from 2d Coulomb interaction
A full, nonperturbative renormalization group analysis of interacting
electrons in a graphite layer is performed, in order to investigate the
deviations from Fermi liquid theory that have been observed in the experimental
measures of a linear quasiparticle decay rate in graphite. The electrons are
coupled through Coulomb interactions, which remain unscreened due to the
semimetallic character of the layer. We show that the model flows towards the
noninteracting fixed-point for the whole range of couplings, with logarithmic
corrections which signal the marginal character of the interaction separating
Fermi liquid and non-Fermi liquid regimes.Comment: 7 pages, 2 Postscript figure
Generalized Galilean Algebras and Newtonian Gravity
The non-relativistic versions of the generalized Poincar\'{e} algebras and
generalized -Lorentz algebras are obtained. This non-relativistic algebras
are called, generalized Galilean algebras type I and type II and denoted by
and
respectively. Using a generalized In\"{o}n\"{u}--Wigner contraction procedure
we find that the generalized Galilean algebras type I can be obtained from the
generalized Galilean algebras type II. The -expansion procedure allows us to
find the algebra from the Newton--Hooke
algebra with central extension. The procedure developed in Ref. \cite{newton}
allow us to show that the non-relativistic limit of the five dimensional
Einstein--Chern--Simons gravity is given by a modified version of the Poisson
equation. The modification could be compatible with the effects of Dark Matter,
which leads us to think that Dark Matter can be interpreted as a
non-relativistic limit of Dark Energy.Comment: 16 pages, no figures in 755 (2016) 433-43
Description with a Screened Potential
Recent lattice QCD calculations suggest a rather abrupt transition in the
confinig potential from a linear to a constant behavior. We analyze the effects
of such a fast deconfinement in the simplest non-relativistic system,
bottomonium.Comment: 4 pages. Presented at MENU04, Beijing 2004. To be published by IJMP
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