7,477 research outputs found
Supersymmetric Fluid Dynamics
Recently Navier-Stokes (NS) equations have been derived from the duality
between the black branes and a conformal fluid on the boundary of AdS_5.
Nevertheless, the full correspondence has to be established between solutions
of supergravity in AdS_5 and supersymmetric field theories on the boundary.
That prompts the construction of NS equations for a supersymmetric fluid. In
the framework of rigid susy, there are several possibilities and we propose one
candidate. We deduce the equations of motion in two ways: both from the
divergenless condition on the energy-momentum tensor and by a suitable
parametrization of the auxiliary fields. We give the complete component
expansion and a very preliminary analysis of the physics of this supersymmetric
fluid.Comment: 24 pages, Latex2
Higher-derivative gauge interactions of Bagger-Lambert-Gustavsson theory in N=1 superspace
We study the structure of the gauge sector of the Bagger-Lambert-Gustavsson
(BLG) theory in the form proposed by van Raamsdonk, adapted to 3D, N=1
superspace. By using the novel Higgs mechanism proposed by Mukhi and
Papageorgakis, we derive the manifestly N=1 supersymmetric higher-order terms
(beyond the supersymmetric Yang-Mills action) that follow from the BLG theory
in its expansion with respect to the inverse gauge coupling constant squared.
We find that all those terms have at least one anti-commutator of the super-YM
field strength superfields as a factor, and thus are reducible to the SYM terms
with the higher (spacetime) derivatives.Comment: 13 pages, LaTeX2e, no figures (title changed, few comments and
references added
Nanocrystal seeding: A low temperature route to polycrystalline Si films
A novel method is presented for growth of polycrystalline silicon films on amorphous substrates at temperatures of 540–575 °C. Grain nucleation and grain growth are performed in two steps, using Si nanocrystals as nuclei ("seeds"). The nanocrystal seeds are produced by excimer laser photolysis of disilane in a room temperature flow cell. Film (grain) growth occurs epitaxially on the seeds in a separate thermal chemical vapor deposition (CVD) step, with growth rates 10–100 times higher than similar CVD growth rates on crystal Si. Grain size and CVD growth rates are dependent on seed coverage, for seed coverage <0.2 monolayers
D=(2+1) O(N) Wess-Zumino model in a large N limit
Using the superfield formalism, the effective Kahlerian superpotential of the
massless \cal{N}=1 O(N) Wess-Zumino model is computed in the limit of large N,
in three spacetime dimensions. The effective Kahlerian superpotential is
evaluated at the subleading order in the 1/N expansion, which involves diagrams
up to two-loop order, for a small coupling constant. We show that the O(N)
symmetry of the model is preserved in this approximation and that no mass is
dynamically generated in the supersymmetric phase. We discuss why spontaneous
O(N) symmetry breaking cannot be induced by radiative corrections in such
model.Comment: 8 pages, 1 figur
Comparison of Some Exact and Perturbative Results for a Supersymmetric SU() Gauge Theory
We consider vectorial, asymptotically free supersymmetric
SU() gauge theories with copies of massless chiral super fields in
various representations and study how perturbative predictions for the lower
boundary of the infrared conformal phase, as a function of , compare with
exact results. We make use of two-loop and three-loop calculations of the beta
function and anomalous dimension of the quadratic chiral super field operator
product for this purpose. The specific chiral superfield contents that we
consider are copies of (i) , (ii) , (iii) ,
and (iv) , where , , , and denote,
respectively, the fundamental, adjoint, and symmetric and antisymmetric rank-2
tensor representations. We find that perturbative results slightly overestimate
the value of relative to the respective exact results for these
representations, i.e., slightly underestimate the interval in for which
the theory has infrared conformal behavior. Our results provide a measure of
how closely perturbative calculations reproduce exact results for these
theories.Comment: 16 pages, 3 figure
Seeking the Loop Quantum Gravity Barbero-Immirzi Parameter and Field in 4D, = 1 Supergravity
We embed the Loop Quantum Gravity Barbero-Immirzi parameter and field within
an action describing 4D, = 1 supergravity and thus within a Low Energy
Effective Action of Superstring/M-Theory. We use the fully gauge-covariant
description of supergravity in (curved) superspace. The gravitational constant
is replaced with the vacuum expectation value of a scalar field, which in local
supersymmetry is promoted to a complex, covariantly chiral scalar superfield.
The imaginary part of this superfield couples to a supersymmetric Holst term.
The Holst term also serves as a starting point in the Loop Quantum Gravity
action. This suggest the possibility of a relation between Loop Quantum Gravity
and supersymmetric string theory, where the Barbero-Immirzi parameter and field
of the former play the role of the supersymmetric axion in the latter. Adding
matter fermions in Loop Quantum Gravity may require the extension of the Holst
action through the Nieh-Yan topological invariant, while in pure, matter-free
supergravity their supersymmetric extensions are the same. We show that, when
the Barbero-Immirzi parameter is promoted to a field in the context of 4D
supergravity, it is equivalent to adding a dynamical complex chiral
(dilaton-axion) superfield with a non-trivial kinetic term (or K\"ahler
potential), coupled to supergravity.Comment: 20 pages, 1 figure. Replaced with accepted version in Phys. Rev.
Effective action of beta-deformed N=4 SYM theory and AdS/CFT
We compute the one-loop effective action in \N=1 conformal SU(N) gauge theory
which is an exactly marginal deformation of the \N=4 SYM theory. We consider an
abelian background of constant \N = 1 gauge field and single chiral scalar.
While for finite N the effective action depends non-trivially on the
deformation parameter \beta, this dependence disappears in the large N limit if
the parameter \beta is real. This conclusion matches the strong-coupling
prediction coming from the form of a D3-brane probe action in the dual
supergravity background: for the simplest choice of the D3-brane position the
probe action happens to be the same as for a D3-brane in AdS_5 x S^5 placed
parallel to the boundary of AdS_5. This suggests that in the real \beta
deformation case there exists a large N non-renormalization theorem for the
4-derivative term in the action.Comment: 15 pages, no figures. V2: comments, reference added. V3: the version
to appear in PR
Infrared ground-based astronomy with the Hughes 256 X 256 PtSi array
It is shown that large format PtSi Schottky diode infrared arrays, the Hughes 256 X 256 hybrid Schottky array in particular, are competitive alternatives to the smaller format photovoltaic arrays for ground-based astronomy. The modest quantum efficiency of the PtSi compared to the photovoltaic devices is more than compensated for by the larger format. The use of hybrid technology yields effective fill factors of nearly 100 percent, and the low dark current, noise, excellent imaging characteristics, cost, and solid nitrogen operating temperature add to the effectiveness of this array for ground-based imaging. In addition to discussing the characteristics of this array, researchers present laboratory test data and astronomical results achieved at Kitt Peak
Embedding (R+R^2)-Inflation into Supergravity
We find the natural embedding of the (R+R^2)-inflationary model into the
recently constructed N=1 F(\cal R)-supergravity. It gives a simple and viable
realization of chaotic inflation in supergravity. The only requirement for a
slow-roll inflation is the existence of the (\cal R)^3-term with an anomalously
large coefficient in Taylor expansion of the F(\cal R) function, where \cal R
is the covariantly-chiral scalar supercurvature superfield.Comment: 4 pages, revtex, no figures (very minor additions, a reference added
Perturbative finiteness of the three-dimensional Susy QED to all orders
Within the superfield formalism, we study the ultraviolet properties of the
three-dimensional supersymmetric quantum electrodynamics. The theory is shown
to be finite at all loops orders in a particular gauge.Comment: 8 pages, 3 figures, revtex
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