317 research outputs found
The Effective Potential of the N=0* Yang-Mills Theory
We study the \N=4 SYM theory with SU(N) gauge group in the large N limit,
deformed by giving equal mass to the four adjoint fermions. With this
modification, a potential is dynamically generated for the six scalars in the
theory, \phi^i. We show that the resulting theory is stable (perturbatively in
the 't Hooft coupling), and that there are some indications that =0 is
the vacuum of the theory. Using the AdS/CFT correspondence, we compare the
results to the corresponding supergravity computation, i.e. brane probing a
deformed AdS_5 x S^5 background, and we find qualitative agreement.Comment: 12 pages, 2 figures, version to appear in JHE
Casimir forces from a loop integral formulation
We reformulate the Casimir force in the presence of a non-trivial background.
The force may be written in terms of loop variables, the loop being a curve
around the scattering sites. A natural path ordering of exponentials take place
when a particular representation of the scattering centres is given. The basic
object to be evaluated is a reduced (or abbreviated) classical pseudo-action
that can be operator valued.Comment: references added, text clarified in place
Three-Form Flux with N=2 Supersymmetry on AdS_5 x S^5
In the context of the AdS/CFT correspondence the general form of a three-form
flux perturbation to the AdS_5 x S^5 solution in the type IIB supergravity
which preserves N=2 supersymmetry is obtained. The arbitrary holomorphic
function appearing in the N=1 case studied by Grana and Polchinski is
restricted to a quadratic function of the coordinates transverse to the
D3-branes.Comment: 11 pages, LaTe
Space-time dependent couplings in N=1 SUSY gauge theories: Anomalies and Central Functions
We consider N=1 supersymmetric gauge theories in which the couplings are
allowed to be space-time dependent functions. Both the gauge and the
superpotential couplings become chiral superfields. As has recently been shown,
a new topological anomaly appears in models with space-time dependent gauge
coupling. Here we show how this anomaly may be used to derive the NSVZ beta
function in a particular, well-determined renormalisation scheme, both without
and with chiral matter. Moreover we extend the topological anomaly analysis to
theories coupled to a classical curved superspace background, and use it to
derive an all-order expression for the central charge c, the coefficient of the
Weyl tensor squared contribution to the conformal anomaly. We also comment on
the implications of our results for the central charge a expected to be of
relevance for a four-dimensional C-theorem.Comment: 28 pages, LaTeX, no figure
Gauge-gravity correspondence in de Sitter braneworld
We study the braneworld solutions based on a solvable model of 5d gauged
supergravity with two scalars of conformal dimension three, which correspond to
bilinear operators of fermions in the dual super Yang-Mills
theory on the boundary. An accelerating braneworld solution is obtained when
both scalars are taken as the form of deformations of the super Yang-Mills
theory and the bulk supersymmetry is broken. This solution is smoothly
connected to the Poincare invariant brane in the limit of vanishing
cosmological constant. The stability of this brane-solution and the
correspondence to the gauge theory are addressed.Comment: 16 pages, 1 figur
Embedding massive flavor in ABJM
We add massive fundamental matter to the ABJM model by adding D6-branes
wrapped asymptotically over RP3. We find two types of solutions at finite
temperature, one that enters the black hole and one that ends before the black
hole. We analyze the behavior of the free energy as a function of temperature,
and find that the system exhibits a phase transition between the two types of
solutions, similar to what happens in the D3-D7 system. We also analyze the
meson spectrum in the model and find several massive scalar modes, again, quite
like the D3-D7 system. We end with a calculation of the conductivities in the
two phases.Comment: 26 pages, 6 figures; version published in JHE
The Structure of the Non-SUSY Baryonic Branch of Klebanov-Strassler
We study the two-dimensional space of supergravity solutions corresponding to
non-supersymmetric deformations of the baryonic branch of Klebanov-Strassler.
By combining analytical methods with a numerical survey of the parameter space,
we find that this solution space includes as limits the softly-broken N=1
solutions of Gubser et al. and those of Dymarsky and Kuperstein. We also
identify a one-dimensional family of solutions corresponding to a natural
non-supersymmetric generalisation of Klebanov-Strassler, and one corresponding
to the limit in which supersymmetry is completely absent, even in the far UV.
For almost all of the parameter space we find indications that much of the
structure of the supersymmetric baryonic branch survives.Comment: 29 pages plus appendices, 11 figure
Integrable Open Spin Chains in Defect Conformal Field Theory
We demonstrate that the one-loop dilatation generator for the scalar sector
of a certain perturbation of N=4 Super Yang-Mills with fundamentals is the
Hamiltonian of an integrable spin chain with open boundary conditions. The
theory is a supersymmetric defect conformal field theory (dCFT) with the
fundamentals in hypermultiplets confined to a codimension one defect. We obtain
a K-matrix satisfying a suitably generalized form of the boundary Yang-Baxter
equation, study the Bethe ansatz equations and demonstrate how Dirichlet and
Neumann boundary conditions arise in field theory, and match to existing
results in the plane wave limit.Comment: 26 pages, LaTeX. v2: references added, typos correcte
Witten-Veneziano from Green-Schwarz
We consider the U(1) problem within the AdS/CFT framework. We explain how the
Witten-Veneziano formula for the eta' mass is related to a generalized
Green-Schwarz mechanism. The closed string mode, that cancels the anomaly of
the gauged U(1) axial symmetry, is identified with the eta' meson. In a
particular set-up of D3-branes on a C3/(Z3xZ3) orbifold singularity, the eta'
meson is a twisted-sector R-R field.Comment: 10 pages, LaTex. 1 eps figure. v2: minor changes, refs. added, to
appear in JHE
Unsweetened Natural Cocoa Powder: A Potent Nutraceutical in Perspective
Unsweetened natural cocoa powder is a pulverized high-grade powder of compressed solid blocks which remains after extraction and removal of the cocoa butter. The authors determined the elementary composition of UNCP, investigated its effect on nitric oxide levels, toxicity, and its protective effect on the heart, kidney, and liver during simultaneous administration with high dose (HD) artemether/lumefantrine (A/L). Macro- and microelements in UNCP were analyzed with energy dispersive x-ray fluorescence spectroscopy (EDXRF). Adult male guinea pigs were administered various doses of UNCP alone and also simultaneously with A/L. Phytochemical analysis of UNCP showed the presence of saponins, flavonoids, tannins, cardiac glycosides, and 38 macro- and microelements. Histopathological analysis showed no toxic effect on the heart, liver, kidney, lungs, testis, and spleen. Administration of various doses of UNCP increased white blood cell counts and lymphocyte count (p > 0.05) compared with the controls. Additionally, UNCP and A/L combination caused an increase in nitric oxide levels when compared with the control group and restores some hematological disorders induced by the 3-day HD A/L administration. Even though UNCP appears to be relatively safe, care should be taken due to the high content of copper element to avoid the possibility of intestinal lining erosion
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