11,178 research outputs found
Landau Ghosts and Anti-Ghosts in Condensed Matter and High Density Hadronic Matter
It is observed that the ``ghost'' (originally discovered by Landau in quantum
electro-dynamics) and its counterparts in other theories are indeed ubiquitous
as they occur in a one-loop approximation to any conventional (unbroken) gauge
theory. The mechanism is first exposed in its generality via the Dyson equation
and a simple but explicit example in condensed matter is provided through the
static Clausius-Mossotti and its dynamic counterpart the Lorenz-Lorentz
equation. The physical phase transition phenomenon associated with it is found
to be super-radiance. We verify quantitatively that water (and many other polar
liquids) are indeed super-radiant at room temperature. In quantum
chromo-dynamics on the other hand, we encounter, thanks to asymptotic freedom,
an ``anti-ghost'' which is closely associated with color confinement. Thus, in
QCD, free quarks and glue exist in a super-radiant phase and hadronic matter in
the normal one.Comment: LaTeX 12 Pages and 2 *.eps Figure
Formation of a rotating jet during the filament eruption on 10-11 April 2013
We analyze multi-wavelength and multi-viewpoint observations of a helically
twisted plasma jet formed during a confined filament eruption on 10-11 April
2013. Given a rather large scale event with its high spatial and temporal
resolution observations, it allows us to clearly understand some new physical
details about the formation and triggering mechanism of twisting jet. We
identify a pre-existing flux rope associated with a sinistral filament, which
was observed several days before the event. The confined eruption of the
filament within a null point topology, also known as an Eiffel tower (or
inverted-Y) magnetic field configuration results in the formation of a twisted
jet after the magnetic reconnection near a null point. The sign of helicity in
the jet is found to be the same as that of the sign of helicity in the
filament. Untwisting motion of the reconnected magnetic field lines gives rise
to the accelerating plasma along the jet axis. The event clearly shows the
twist injection from the pre-eruptive magnetic field to the jet.Comment: 14 pages, 12 figures, to appear in MNRA
Spectroscopic Observations and Modelling of Impulsive Alfv\'en Waves Along a Polar Coronal Jet
Using the Hinode/EIS 2 spectroscopic observations, we study the intensity,
velocity, and FWHM variations of the strongest Fe XII 195.12 \AA\ line along
the jet to find the signature of Alfv\'en waves. We simulate numerically the
impulsively generated Alfv\'en waves within the vertical Harris current-sheet,
forming the jet plasma flows, and mimicking their observational signatures.
Using the FLASH code and the atmospheric model with embedded weakly expanding
magnetic field configuration within a vertical Harris current-sheet, we solve
the two and half-dimensional (2.5-D) ideal magnetohydrodynamic (MHD) equations
to study the evolution of Alfv\'en waves and vertical flows forming the plasma
jet. At a height of from the base of the jet, the
red-shifted velocity component of Fe XII 195.12 \AA\ line attains its maximum
() which converts into a blue-shifted one between the
altitude of . The spectral intensity continously increases up
to , while FWHM still exhibits the low values with almost
constant trend. This indicates that the reconnection point within the jet's
magnetic field topology lies in the corona from its
footpoint anchored in the Sun's surface. Beyond this height, FWHM shows a
growing trend. This may be the signature of Alfv\'en waves that impulsively
evolve due to reconnection and propagate along the jet. From our numerical
data, we evaluate space- and time- averaged Alfv\'en waves velocity amplitudes
at different heights in the jet's current-sheet, which contribute to the
non-thermal motions and spectral line broadening. The synthetic width of Fe XII
line exhibits similar trend of increment as in the
observational data, possibly proving the existence of impulsively generated (by
reconnection) Alfv\'en waves which propagate along the jet
On Thermal-Pulse-Driven Plasma Flows in Coronal Funnels as Observed by Hinode/EUV Imaging Spectrometer (EIS)
Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging
Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open
and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler
velocity map of Fe XII 195.120 A shows that the diffuse close-loop system to be
mostly red-shifted. The open arches (funnels) at the eastern boundary of AR
exhibit blue-shifts with a maximum speed of about 10-15 km/s. This implies
outflowing plasma through these magnetic structures. In support of these
observations, we perform a 2D numerical simulation of the expanding coronal
funnels by solving the set of ideal MHD equations in appropriate VAL-III C
initial temperature conditions using the FLASH code. We implement a rarefied
and hotter region at the footpoint of the model funnel, which results in the
evolution of slow plasma perturbations propagating outward in the form of
plasma flows. We conclude that the heating, which may result from magnetic
reconnection, can trigger the observed plasma outflows in such coronal funnels.
This can transport mass into the higher corona, giving rise to the formation of
the nascent solar wind.Comment: 17 Pages; 7 Figure
- …