1,164 research outputs found
Ground States of S-duality Twisted N=4 Super Yang-Mills Theory
We study the low-energy limit of a compactification of N=4 U(n) super
Yang-Mills theory on with boundary conditions modified by an S-duality
and R-symmetry twist. This theory has N=6 supersymmetry in 2+1D. We analyze the
compactification of this 2+1D theory by identifying a dual weakly coupled
type-IIA background. The Hilbert space of normalizable ground states is
finite-dimensional and appears to exhibit a rich structure of sectors. We
identify most of them with Hilbert spaces of Chern-Simons theory (with
appropriate gauge groups and levels). We also discuss a realization of a
related twisted compactification in terms of the (2,0)-theory, where the recent
solution by Gaiotto and Witten of the boundary conditions describing D3-branes
ending on a (p,q) 5-brane plays a crucial role.Comment: 104 pages, 5 figures. Revisions to subsection (6.6) and other minor
corrections included in version
A likely detection of a local interplanetary dust cloud passing near the Earth in the AKARI mid-infrared all-sky map
Context. We are creating the AKARI mid-infrared all-sky diffuse maps. Through
a foreground removal of the zodiacal emission, we serendipitously detected a
bright residual component whose angular size is about 50 x 20 deg. at a
wavelength of 9 micron. Aims. We investigate the origin and the physical
properties of the residual component. Methods. We measured the surface
brightness of the residual component in the AKARI mid-infrared all-sky maps.
Results. The residual component was significantly detected only in 2007
January, even though the same region was observed in 2006 July and 2007 July,
which shows that it is not due to the Galactic emission. We suggest that this
may be a small cloud passing near the Earth. By comparing the observed
intensity ratio of I_9um/I_18um with the expected intensity ratio assuming
thermal equilibrium of dust grains at 1 AU for various dust compositions and
sizes, we find that dust grains in the moving cloud are likely to be much
smaller than typical grains that produce the bulk of the zodiacal light.
Conclusions. Considering the observed date and position, it is likely that it
originates in the solar coronal mass ejection (CME) which took place on 2007
January 25.Comment: 5 pages, 4 figures, accepted by Astronomy and Astrophysic
One-Parameter Squeezed Gaussian States of Time-Dependent Harmonic Oscillator and Selection Rule for Vacuum States
By using the invariant method we find one-parameter squeezed Gaussian states
for both time-independent and time-dependent oscillators. The squeezing
parameter is expressed in terms of energy expectation value for
time-independent case and represents the degree of mixing positive and negative
frequency solutions for time-dependent case. A {\it minimum uncertainty
proposal} is advanced to select uniquely vacuum states at each moment of time.
We show that the Gaussian states with minimum uncertainty coincide with the
true vacuum state for time-independent oscillator and the Bunch-Davies vacuum
for a massive scalar field in a de Sitter spacetime.Comment: 13 Pages, ReVTeX, no figure
A Micro Molecular Bipolar Outflow From HL Tau
We present detailed geometry and kinematics of the inner outflow toward HL
Tau observed using Near Infrared Integral Field Spectograph (NIFS) at the
Gemini-North 8-m Observatory. We analyzed H2 2.122 um emission and [Fe II]
1.644 um line emission as well as the adjacent continuum observed at a <0".2
resolution. The H2 emission shows (1) a bubble-like geometry to the northeast
of the star, as briefly reported in the previous paper, and (2) faint emission
in the southwest counterflow, which has been revealed through careful analysis.
The emission on both sides of the star show an arc 1".0 away from the star,
exhibiting a bipolar symmetry. Different brightness and morphologies in the
northeast and southwest flows are attributed to absorption and obscuration of
the latter by a flattened envelope and a circumstellar disk. The H2 emission
shows a remarkably different morphology from the collimated jet seen in [Fe II]
emission. The positions of some features coincide with scattering continuum,
indicating that these are associated with cavities in the dusty envelope. Such
properties are similar to millimeter CO outflows, although the spatial scale of
the H2 outflow in our image (~150 AU) is strikingly smaller than the mm
outflows, which often extend over 1000-10000 AU scales. The position-velocity
diagram of the H2 and [Fe II] emission do not show any evidence for kinematic
interaction between these flows. All results described above support the
scenario that the jet is surrounded by an unseen wide-angled wind, which
interacts with the ambient gas and produce the bipolar cavity and shocked H2
emission.Comment: 13 pages, 4 figures, accepted for publication in ApJ
Lanczos exact diagonalization study of field-induced phase transition for Ising and Heisenberg antiferromagnets
Using an exact diagonalization treatment of Ising and Heisenberg model
Hamiltonians, we study field-induced phase transition for two-dimensional
antiferromagnets. For the system of Ising antiferromagnet the predicted
field-induced phase transition is of first order, while for the system of
Heisenberg antiferromagnet it is the second-order transition. We find from the
exact diagonalization calculations that the second-order phase transition
(metamagnetism) occurs through a spin-flop process as an intermediate step.Comment: 4 pages, 4 figure
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Mulsemedia: State of the art, perspectives, and challenges
Mulsemedia-multiple sensorial media-captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum-from virtual reality applications to computer games-as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome
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