1,745 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
The X-ray puzzle of the L1551 IRS 5 jet
Protostars are actively accreting matter and they drive spectacular, dynamic
outflows, which evolve on timescales of years. X-ray emission from these jets
has been detected only in a few cases and little is known about its time
evolution. We present a new Chandra observation of L1551 IRS 5's jet in the
context of all available X-ray data of this object. Specifically, we perform a
spatially resolved spectral analysis of the X-ray emission and find that (a)
the total X-ray luminosity is constant over almost one decade, (b) the majority
of the X-rays appear to be always located close to the driving source, (c)
there is a clear trend in the photon energy as a function of the distance to
the driving source indicating that the plasma is cooler at larger distances and
(d) the X-ray emission is located in a small volume which is unresolved
perpendicular to the jet axis by Chandra. A comparison of our X-ray data of the
L1551 IRS 5 jet both with models as well as X-ray observations of other
protostellar jets shows that a base/standing shock is a likely and plausible
explanation for the apparent constancy of the observed X-ray emission. Internal
shocks are also consistent with the observed morphology if the supply of jet
material by the ejection of new blobs is sufficiently constant. We conclude
that the study of the X-ray emission of protostellar jet sources allows us to
diagnose the innermost regions close to the acceleration region of the
outflows.Comment: A&A accepted, 14 pages, 9 figure
An Empirical Study on User Satisfaction with Mobile Business Applications Use and Hedonism
Numerous recent information systems (IS), such as instant messaging and mobile applications, are first developed within an individual context and then widely used in both individual and organizational contexts. The present study examines a recent IS, mobile business (m-business) applications, used within organizations and reports the impact of the users’ pleasurable emotions or feelings on users’ satisfaction with IS. The result from the sample survey and an existential phenomenology indicates that hedonism is a significant determinant of satisfaction with m-business applications. By providing insight into how and why individuals are satisfied or dissatisfied with m-business applications in addition to what leads to this, the authors hope the findings of this study will assist researchers and practitioners in finding major barriers to the mobile business application use in order to design better applications for improved user satisfaction
Ricci Flat Black Holes and Hawking-Page Phase Transition in Gauss-Bonnet Gravity and Dilaton Gravity
It is well-known that there exists a Hawking-Page phase transition between a
spherical AdS black hole and a thermal AdS space. The phase transition does not
happen between a Ricci flat AdS black hole whose horizon is a Ricci flat space
and a thermal AdS space in the Poincare coordinates. However, the Hawking-Page
phase transition occurs between a Ricci flat AdS black hole and an AdS soliton
if at least one of horizon coordinates for the Ricci flat black hole is
compact. We show a similar phase transition betwen the Ricci flat black holes
and deformed AdS solitons in the Gauss-Bonnet gravity and the dilaton gravity
with a Liouville-type potential including the gauged supergravity coming from
the spherical reduction of Dp-branes in type II supergravity. In contrast to
Einstein gravity, we find that the high temperature phase can be dominated
either by black holes or deformed AdS solitons depending on parameters.Comment: Latex, 17 pages without figure
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