549 research outputs found
A Single Scale Theory for Cold and Hot Dark Matter
We show that a recently proposed extension of the MSSM can provide a scenario
where both the cold and hot dark matter of the universe owe their origin to a
single scale connected with the breakdown of the global B-L symmetry. The susy
partner of the majoron and the light Majorana neutrinos are the cold and hot
dark matter candidates respectively in this model and their desired relative
abundances emerge when the scale of B-L symmetry breaking is in the TeV range.Comment: UMD-PP-94-102 (latex file; 15 pages
Numerical Simulation of Vortex Crystals and Merging in N-Point Vortex Systems with Circular Boundary
In two-dimensional (2D) inviscid incompressible flow, low background
vorticity distribution accelerates intense vortices (clumps) to merge each
other and to array in the symmetric pattern which is called ``vortex
crystals''; they are observed in the experiments on pure electron plasma and
the simulations of Euler fluid. Vortex merger is thought to be a result of
negative ``temperature'' introduced by L. Onsager. Slight difference in the
initial distribution from this leads to ``vortex crystals''. We study these
phenomena by examining N-point vortex systems governed by the Hamilton
equations of motion. First, we study a three-point vortex system without
background distribution. It is known that a N-point vortex system with boundary
exhibits chaotic behavior for N\geq 3. In order to investigate the properties
of the phase space structure of this three-point vortex system with circular
boundary, we examine the Poincar\'e plot of this system. Then we show that
topology of the Poincar\'e plot of this system drastically changes when the
parameters, which are concerned with the sign of ``temperature'', are varied.
Next, we introduce a formula for energy spectrum of a N-point vortex system
with circular boundary. Further, carrying out numerical computation, we
reproduce a vortex crystal and a vortex merger in a few hundred point vortices
system. We confirm that the energy of vortices is transferred from the clumps
to the background in the course of vortex crystallization. In the vortex
merging process, we numerically calculate the energy spectrum introduced above
and confirm that it behaves as k^{-\alpha},(\alpha\approx 2.2-2.8) at the
region 10^0<k<10^1 after the merging.Comment: 30 pages, 11 figures. to be published in Journal of Physical Society
of Japan Vol.74 No.
Quasi-stationary States of Two-Dimensional Electron Plasma Trapped in Magnetic Field
We have performed numerical simulations on a pure electron plasma system
under a strong magnetic field, in order to examine quasi-stationary states that
the system eventually evolves into. We use ring states as the initial states,
changing the width, and find that the system evolves into a vortex crystal
state from a thinner-ring state while a state with a single-peaked density
distribution is obtained from a thicker-ring initial state. For those
quasi-stationary states, density distribution and macroscopic observables are
defined on the basis of a coarse-grained density field. We compare our results
with experiments and some statistical theories, which include the
Gibbs-Boltzmann statistics, Tsallis statistics, the fluid entropy theory, and
the minimum enstrophy state. From some of those initial states, we obtain the
quasi-stationary states which are close to the minimum enstrophy state, but we
also find that the quasi-stationary states depend upon initial states, even if
the initial states have the same energy and angular momentum, which means the
ergodicity does not hold.Comment: 9 pages, 7 figure
Neutrinoless Double Beta Decay in Supersymmetric Seesaw model
Inspired by the recent HEIDELBERG-MOSCOW double beta decay experiment, we
discuss the neutrinoless double beta decay in the supersymmetric seesaw model.
Our numerical analysis indicates that we can naturally explain the data of the
observed neutrinoless double beta decay, as well as that of the solar and
atmospheric neutrino experiments with at least one Majorana-like sneutrino of
middle energy scale in the model.Comment: latex, 25 pages, include 5 figures, final version in Phys. Rev.
âIt's my language, my culture and it's personal!â Migrant mothers' experience of language use and identity change in their relationship with their children: an interpretative phenomenological analysis
The question of how migrantsâ language use impacts their ethnic identity has received considerable attention in the literature. There is, however, little understanding of how this relationship manifests or is negotiated in interethnic families. This paper presents an in-depth exploration of Spanish mothersâ experiences of Spanish- and English-language interactions with their English-born children. Semi-structured interviews were conducted with Spanish mothers living in Britain in interethnic partnerships and transcripts were subjected to interpretative phenomenological analysis. Analysis reveals a process of identity change where participantsâ shifting ethnic identifications with host and heritage culture is intimately related to their language use with their children. Pivotal to this process is the participantsâ need to maintain their âSpanish motherâ identity, a desire that can only be fulfilled by transferring their heritage language to their children and speaking it with them. Findings reveal how this dynamic impacts perception of family roles, relationship quality and psychological well-being
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