7,834 research outputs found
N=2 Rigid Supersymmetry with Gauged Central Charge
We develop a general setting for N=2 rigid supersymmetric field theories with
gauged central charge in harmonic superspace. We consider those N=2 multiplets
which have a finite number of off-shell components and exist off shell owing to
a non-trivial central charge. This class includes, in particular, the
hypermultiplet with central charge and various versions of the vector-tensor
multiplet. For such theories we present a manifestly supersymmetric universal
action. Chern-Simons couplings to an external N=2 super Yang-Mills multiplet
are given, in harmonic superspace, for both the linear and nonlinear
vector-tensor multiplets with gauged central charge. We show how to deduce the
linear version of the vector-tensor multiplet from six dimensions.Comment: 46 pages, latex, no figure
On The spectrum of a Noncommutative Formulation of the D=11 Supermembrane with Winding
A regularized model of the double compactified D=11 supermembrane with
nontrivial winding in terms of SU(N) valued maps is obtained. The condition of
nontrivial winding is described in terms of a nontrivial line bundle introduced
in the formulation of the compactified supermembrane. The multivalued
geometrical objects of the model related to the nontrivial wrapping are
described in terms of a SU(N) geometrical object which in the
limit, converges to the symplectic connection related to the area preserving
diffeomorphisms of the recently obtained non-commutative description of the
compactified D=11 supermembrane.(I. Martin, J.Ovalle, A. Restuccia. 2000,2001)
The SU(N) regularized canonical lagrangian is explicitly obtained. In the limit it converges to the lagrangian in (I.Martin, J.Ovalle,
A.Restuccia. 2000,2001) subject to the nontrivial winding condition. The
spectrum of the hamiltonian of the double compactified D=11 supermembrane is
discussed.
Generically, it contains local string like spikes with zero energy.
However the sector of the theory corresponding to a principle bundle
characterized by the winding number , described by the SU(N) model we
propose, is shown to have no local string-like spikes and hence the spectrum of
this sector should be discrete.Comment: 16 pages.Latex2
Consistent truncation of d = 11 supergravity on AdS_4 x S^7
We study the system of equations derived twenty five years ago by B. de Wit
and the first author [Nucl. Phys. B281 (1987) 211] as conditions for the
consistent truncation of eleven-dimensional supergravity on AdS_4 x S^7 to
gauged N = 8 supergravity in four dimensions. By exploiting the E_7(7)
symmetry, we determine the most general solution to this system at each point
on the coset space E_7(7)/SU(8). We show that invariants of the general
solution are given by the fluxes in eleven-dimensional supergravity. This
allows us to both clarify the explicit non-linear ansatze for the fluxes given
previously and to fill a gap in the original proof of the consistent
truncation. These results are illustrated with several examples.Comment: 41 pages, typos corrected, published versio
A Topologically Massive Gauge Theory with 32 Supercharges
We construct a novel topologically massive abelian Chern-Simons gauge theory
with 32 global supersymmetries in three spacetime dimensions. In spite of the
32 supercharges, the theory exhibits massive excitations only up to spin 1. The
possibility of such a multiplet shortening is due to the presence of
non-central R-symmetry generators in the Poincare superalgebra, whose
supermultiplets are determined.Comment: 20 pages; v2: minor changes, ref. added, to appear in Phys. Rev.
On BPS bounds in D=4 N=2 gauged supergravity II: general matter couplings and black hole masses
We continue the analysis of BPS bounds started in arXiv:1110.2688, extending
it to the full class of N=2 gauged supergravity theories with arbitrary vector
and hypermultiplets. We derive the general form of the asymptotic charges for
asymptotically flat (M_4), anti-de Sitter (AdS_4), and magnetic anti-de Sitter
(mAdS_4) spacetimes. Some particular examples from black hole physics are given
to explicitly demonstrate how AdS and mAdS masses differ when solutions with
non-trivial scalar profiles are considered.Comment: 21 pages; v2 added reference, published version; v3 minor correction
Holographic injection locking of a broad area laser diode via a photorefractive thin-film device
We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency source (Ti:Sapphire laser) while the spatial distribution adapts to the preferred profile of the broad area diode. The result is an injection-locked broad area diode emitting with a linewidth comparable to the Ti:Sapphire laser
The RCB star V854 Cen is surrounded by a hot dusty shell
Aims : The hydrogen-deficient supergiants known as R Coronae Borealis (RCB)
stars might be the result of a double-degenerate merger of two white dwarfs
(WDs), or a final helium shell flash in a planetary nebula central star. In
this context, any information on the geometry of their circumstellar
environment and, in particular, the potential detection of elongated
structures, is of great importance. Methods : We obtained near-IR observations
of V854 Cen with the AMBER recombiner located at the Very Large Telescope
Interferometer (VLTI) array with the compact array (B35m) in 2013 and the
long array (B140m) in 2014. At each time, V854 Cen was at maximum light.
The - and -band continua were investigated by means of spectrally
dependant geometric models. These data were supplemented with mid-IR VISIR/VLT
images. Results : A dusty slightly elongated over density is discovered both in
the - and -band images. With the compact array, the central star is
unresolved (\,mas), but a flattened dusty environment of mas is discovered whose flux increases from about 20% in the
band to reach about 50% at 2.3\micron, which indicates hot
(T1500\,K) dust in the close vicinity of the star. The major axis is
oriented at a position angle (P.A.) of 12629. Adding the long-array
configuration dataset provides tighter constraints on the star diameter
( mas), a slight increase of the overdensity to
mas and a consistent P.A. of 13349. The closure phases, sensitive to
asymmetries, are null and compatible with a centro-symmetric, unperturbed
environment excluding point sources at the level of 3% of the total flux in
2013 and 2014. The VISIR images exhibit a flattened aspect ratio at the 15-20%
level at larger distances (1\arcsec) with a position angle of
9219, marginally consistent with the interferometric observations.
Conclusions : This is the first time that a moderately elongated structure has
been observed around an RCB star. These observations confirm the numerous
suggestions for a bipolar structure proposed for this star in the literature,
which were mainly based on polarimetric and spectroscopic observations.Comment: Accepted by A\&A, new version after language editing, Astronomy and
Astrophysics (2014
Comparison of Generic and Proprietary Sodium Stibogluconate for the Treatment of Visceral Leishmaniasis in Kenya.
OBJECTIVE: To compare the use of generic and proprietary sodium stibogluconate for the treatment of visceral leishmaniasis (kala-azar). METHODS: A total of 102 patients with confirmed kala-azar were treated in a mission hospital in West Pokot region, Kenya, with sodium stibogluconate (20 mg/kg/day for 30 days)--either as Pentostam (PSM) or generic sodium stibogluconate (SSG); 51 patients were allocated alternately to each treatment group. FINDINGS: There were no significant differences in baseline demographic characteristics or disease severity, or in events during treatment. There were 3 deaths in the PSM group and 1 in the SSG group; 2 patients defaulted in each group. Only 1 out of 80 test-of-cure splenic aspirates was positive for Leishmania spp.; this patient was in the SSG group. Follow-up after > or = 6 months showed that 6 out of 58 patients had relapsed, 5 in the SSG group and 1 in the PSM group. No outcome variable was significantly different between the two groups. CONCLUSION: The availability of cheaper generic sodium stibogluconate, subject to rigid quality controls, now makes it possible for the health authorities in kala-azar endemic areas to provide treatment to many more patients in Africa
Minimal Stability in Maximal Supergravity
Recently, it has been shown that maximal supergravity allows for
non-supersymmetric AdS critical points that are perturbatively stable. We
investigate this phenomenon of stability without supersymmetry from the
sGoldstino point of view. In particular, we calculate the projection of the
mass matrix onto the sGoldstino directions, and derive the necessary conditions
for stability. Indeed we find a narrow window allowing for stable SUSY breaking
points. As a by-product of our analysis, we find that it seems impossible to
perturb supersymmetric critical points into non-supersymmetric ones: there is a
minimal amount of SUSY breaking in maximal supergravity.Comment: 27 pages, 1 figure. v2: two typos corrected, published versio
An active asteroid belt causing the UX Ori phenomenon in RZ Psc
We report the discovery of mid-infrared excess emission in the young object
RZ Psc. The excess constitutes ~8% of its Lbol, and is well fit by a single
500K black-body implying a dust free region within 0.7AU for optically thick
dust. The object displays dust obscuration events (UXOR behaviour) with a
time-scale that suggests dusty material on orbits of 0.5AU. We also report a
12.4 year cyclical photometric variability which can be interpreted as due to
perturbations in the dust distribution. The system is characterized by a high
inclination, marginal extinction (during bright photometric states), a single
temperature for the warm dust, and an age estimate which puts the star beyond
the formation stage. We propose that the dust occultation events present a
dynamical view of an active asteroid belt whose collisional products
sporadically obscure the central star.Comment: Accepted for A&A letter
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