478,519 research outputs found
A new AdS_4/CFT_3 Dual with Extended SUSY and a Spectral Flow
We construct a new AdS_4 background in Type IIB supergravity by means of a
non-Abelian T-duality transformation on the Type IIA dual of ABJM. The analysis
of probe and particle-like branes suggests a dual CFT in which each of the
gauge groups is doubled. A common feature of non-Abelian T-duality is that in
the absence of any global information coming from String Theory it gives rise
to non-compact dual backgrounds, with coordinates living in the Lie algebra of
the Lie group involved in the dualization. In backgrounds with CFT duals this
poses obvious problems to the CFTs. In this paper we show that for the new
AdS_4 background the gauge groups of the associated dual CFT undergo a spectral
flow as the non-compact internal direction runs from 0 to infinity, which
resembles Seiberg duality in N=1. This phenomenon, very reminiscent of the
cascade, provides an interpretation in the CFT for the running of the
non-compact coordinate, and suggests that at the end of the flow the extra
charges disappear and the dual CFT is described by a 2-node quiver very similar
to ABJM, albeit with reduced supersymmetry.Comment: 40 pages, published versio
On linear convergence of a distributed dual gradient algorithm for linearly constrained separable convex problems
In this paper we propose a distributed dual gradient algorithm for minimizing
linearly constrained separable convex problems and analyze its rate of
convergence. In particular, we prove that under the assumption of strong
convexity and Lipshitz continuity of the gradient of the primal objective
function we have a global error bound type property for the dual problem. Using
this error bound property we devise a fully distributed dual gradient scheme,
i.e. a gradient scheme based on a weighted step size, for which we derive
global linear rate of convergence for both dual and primal suboptimality and
for primal feasibility violation. Many real applications, e.g. distributed
model predictive control, network utility maximization or optimal power flow,
can be posed as linearly constrained separable convex problems for which dual
gradient type methods from literature have sublinear convergence rate. In the
present paper we prove for the first time that in fact we can achieve linear
convergence rate for such algorithms when they are used for solving these
applications. Numerical simulations are also provided to confirm our theory.Comment: 14 pages, 4 figures, submitted to Automatica Journal, February 2014.
arXiv admin note: substantial text overlap with arXiv:1401.4398. We revised
the paper, adding more simulations and checking for typo
Holographic Uniformization
We derive and study supergravity BPS flow equations for M5 or D3 branes
wrapping a Riemann surface. They take the form of novel geometric flows
intrinsically defined on the surface. Their dual field-theoretic interpretation
suggests the existence of solutions interpolating between an arbitrary metric
in the UV and the constant-curvature metric in the IR. We confirm this
conjecture with a rigorous global existence proof.Comment: 52 pages, 3 figure
Flow Induced by Dual-Turbine of Different Diameters in a Gas-Liquid Agitation System: the Agitation and Turbulence Indices
Flow induced by a dual turbine stirred tank was characterized measuring local velocities with a LDV and drawing the main velocity fields and the maps of turbulence intensities. The hydrodynamic regime studied in all the experiments was the so-called merging flow regime. Two impeller configurations were studied. In the first one, two disk style turbine of the same dimensions (configuration A) were used, while in the second one, the dimensions of the upper turbine were 20 % proportionally smaller than those of the lower turbine (configuration B). The agitation and turbulence indices were used to evaluate, as a first order approximation, the power consumption distribution between convective and turbulent flows. The comparison of the two-phase agitation systems studied showed that configuration B seems to be more efficient than configuration A, since both induce a similar global convective flow, but the first one assures a significant reduction of power consumption. The distribution of power consumption between convective and turbulent flows was evaluated using the agitation index and a new global parameter: turbulence ind
Emerging Non-Anomalous Baryonic Symmetries in the AdS_5/CFT_4 Correspondence
We study the breaking of baryonic symmetries in the AdS_5/CFT_4
correspondence for D3 branes at Calabi-Yau three-fold singularities. This
leads, for particular VEVs, to the emergence of non-anomalous baryonic
symmetries during the renormalization group flow. We claim that these VEVs
correspond to critical values of the B-field moduli in the dual supergravity
backgrounds. We study in detail the C^3/Z_3 orbifold, the cone over F_0 and the
C^3/Z_5 orbifold. For the first two examples, we study the dual supergravity
backgrounds that correspond to the breaking of the emerging baryonic symmetries
and identify the expected Goldstone bosons and global strings in the infra-red.
In doing so we confirm the claim that the emerging symmetries are indeed
non-anomalous baryonic symmetries.Comment: 65 pages, 15 figures;v2: minor changes, published versio
N=2 Moduli Spaces and N=1 Dualities for SO(n_c) and USp(2n_c) SuperQCD
We determine the exact global structure of the moduli space of
supersymmetric and \USp(2n) gauge theories with matter
hypermultiplets in the fundamental representations, using the
non-renormalization theorem for the Higgs branches and the exact solutions for
the Coulomb branches. By adding an --breaking mass term for the
adjoint chiral field and varying the mass, the theories can be made to
flow to either an ``electric'' supersymmetric QCD or its dual
``magnetic'' version. We thus obtain a derivation of the dualities of
Seiberg.Comment: 20 pages, harvmac (b
Dynamical black holes and expanding plasmas
We analyse the global structure of time-dependent geometries dual to expanding plasmas, considering two examples: the boost invariant Bjorken flow, and the conformal soliton flow. While the geometry dual to the Bjorken flow is constructed in a perturbation expansion at late proper time, the conformal soliton flow has an exact dual (which corresponds to a Poincaré patch of Schwarzschild-AdS). In particular, we discuss the position and area of event and apparent horizons in the two geometries. The conformal soliton geometry offers a sharp distinction between event and apparent horizon; whereas the area of the event horizon diverges, that of the apparent horizon stays finite and constant. This suggests that the entropy of the corresponding CFT state is related to the apparent horizon rather than the event horizon
The Spectrum of Strings on Warped AdS_3 x S^3
String theory on NS-NS AdS_3 x S^3 admits an exactly marginal deformation
which breaks the SL(2,R)_R x SL(2,R)_L isometry of AdS_3 down to SL(2,R)_R x
U(1)_L. The holographic dual is an exotic and only partially understood type of
two-dimensional CFT with a reduced unbroken global conformal symmetry group. In
this paper we study the deformed theory on the string worldsheet. It is found
to be related by a spectral flow which is nonlocal in spacetime to the
undeformed worldsheet theory. An exact formula for the spectrum of massive
strings is presented.Comment: 26 pages, no figure
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