63,370 research outputs found
From the Complete Yang Model to Snyder's Model, de Sitter Special Relativity and Their Duality
By means of Dirac procedure, we re-examine Yang's quantized space-time model,
its relation to Snyder's model, the de Sitter special relativity and their
UV-IR duality. Starting from a dimensionless dS_5-space in a 5+1-d Mink-space a
complete Yang model at both classical and quantum level can be presented and
there really exist Snyder's model, the dS special relativity and the duality.Comment: 7 papge
A non-variational approach to nonlinear stability in stellar dynamics applied to the King model
In previous work by Y. Guo and G. Rein, nonlinear stability of equilibria in
stellar dynamics, i.e., of steady states of the Vlasov-Poisson system, was
accessed by variational techniques. Here we propose a different,
non-variational technique and use it to prove nonlinear stability of the King
model against a class of spherically symmetric, dynamically accessible
perturbations. This model is very important in astrophysics and was out of
reach of the previous techniques
Blow up solutions to a viscoelastic fluid system and a coupled Navier-Stokes/Phase-Field system in R^2
We find explicit solutions to both the Oldroyd-B model with infinite
Weissenberg number and the coupled Navier-Stokes/Phase-Field system. The
solutions blow up in finite time.Comment: 5 page
Recurrent Coronal Jets Induced by Repetitively Accumulated Electric Currents
Three extreme-ultraviolet (EUV) jets recurred in about one hour on 2010
September 17 in the following magnetic polarity of active region 11106. The EUV
jets were observed by the Atmospheric Imaging Assembly (AIA) on board the Solar
Dynamics Observatory (SDO). The Helioseismic and Magnetic Imager (HMI) on board
SDO measured the vector magnetic field, from which we derive the magnetic flux
evolution, the photospheric velocity field, and the vertical electric current
evolution. The magnetic configuration before the jets is derived by the
nonlinear force-free field (NLFFF) extrapolation.
We derive that the jets are above a pair of parasitic magnetic bipoles which
are continuously driven by photospheric diverging flows. The interaction drove
the build up of electric currents that we indeed observed as elongated patterns
at the photospheric level. For the first time, the high temporal cadence of HMI
allows to follow the evolution of such small currents. In the jet region, we
found that the integrated absolute current peaks repetitively in phase with the
171 A flux evolution. The current build up and its decay are both fast, about
10 minutes each, and the current maximum precedes the 171 A by also about 10
minutes. Then, HMI temporal cadence is marginally fast enough to detect such
changes.
The photospheric current pattern of the jets is found associated to the
quasi-separatrix layers deduced from the magnetic extrapolation. From previous
theoretical results, the observed diverging flows are expected to build
continuously such currents. We conclude that magnetic reconnection occurs
periodically, in the current layer created between the emerging bipoles and the
large scale active region field. It induced the observed recurrent coronal jets
and the decrease of the vertical electric current magnitude.Comment: 10 pages, 7 figures, accepted for publication in A&
Effective generation of Ising interaction and cluster states in coupled microcavities
We propose a scheme for realizing the Ising spin-spin interaction and atomic
cluster states utilizing trapped atoms in coupled microcavities. It is shown
that the atoms can interact with each other via the exchange of virtual photons
of the cavities. Through suitably tuning the parameters, an effective Ising
spin-spin interaction can be generated in this optical system, which is used to
produce the cluster states. This scheme does not need the preparation of
initial states of atoms and cavity modes, and is insensitive to cavity decay.Comment: 11pages, 2 figures, Revtex
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