26,529 research outputs found

### The Gauge Dual of Gauged N=8 Supergravity Theory

The most general SU(3)-singlet space of gauged N=8 supergravity in
four-dimensions is studied recently. The SU(3)-invariant six scalar fields are
realized by six real four-forms. A family of holographic N=1 supersymmetric RG
flows on M2-branes in three-dimensions is described. This family of flows is
driven by three independent mass parameters from the N=8 SO(8) theory and is
controlled by two IR fixed points, N=1 G_2-invariant one and N=2 SU(3) x
U(1)-invariant one. The generic flow with arbitrary mass parameters is N=1
supersymmetric and reaches to the N=2 SU(3) x U(1) fixed point where the three
masses become identical. A particular N=1 supersymmetric SU(3)-preserving RG
flow from the N=1 G_2-invariant fixed point to the N=2 SU(3) x U(1)-invariant
fixed point is also discussed.Comment: 19pp; added the footnote 1, improved the conclusion and to appear in
IJMP

### Perturbing Around A Warped Product Of AdS_4 and Seven-Ellipsoid

We compute the spin-2 Kaluza-Klein modes around a warped product of AdS_4 and
a seven-ellipsoid. This background with global G_2 symmetry is related to a
U(N) x U(N) N=1 superconformal Chern-Simons matter theory with sixth order
superpotential. The mass-squared in AdS_4 is quadratic in G_2 quantum number
and KK excitation number. We determine the dimensions of spin-2 operators using
the AdS/CFT correspondence. The connection to N=2 theory preserving SU(3) x
U(1)_R is also discussed.Comment: 21pp; The second and last paragraphs of section 2, the footnotes 1
and 2 added and to appear in JHE

### Meta-Stable Brane Configurations by Higher Order Polynomial Superpotential

We construct the type IIA nonsupersymmetric meta-stable brane configuration
consisting of (2k+1) NS5-branes and D4-branes where the electric gauge theory
superpotential has an order (2k+2) polynomial for the bifundamentals. We find a
rich pattern of nonsupersymmetric meta-stable states as well as the
supersymmetric stable ones. By adding the orientifold 4-plane to this brane
configuration, we also describe the intersecting brane configuration of type
IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of
corresponding gauge theory.Comment: 27pp, 8 figures; some footnotes added; to appear in IJMP

### Explicit Construction of Spin 4 Casimir Operator in the Coset Model $\hat{SO} (5)_{1} \times \hat{SO} (5)_{m} / \hat{SO} (5)_{1+m}$

We generalize the Goddard-Kent-Olive (GKO) coset construction to the
dimension 5/2 operator for $\hat{so} (5)$ and compute the fourth order
Casimir invariant in the coset model $\hat{SO} (5)_{1} \times \hat{SO}
(5)_{m} / \hat{SO} (5)_{1+m}$ with the generic unitary minimal $c < 5/2$
series that can be viewed as perturbations of the $m \rightarrow \infty$
limit, which has been investigated previously in the realization of $c= 5/2$
free fermion model.Comment: 11 page

### Meta-Stable Brane Configurations by Adding an Orientifold-Plane to Giveon-Kutasov

In hep-th/0703135, they have found the type IIA intersecting brane
configuration where there exist three NS5-branes, D4-branes and anti-D4-branes.
By analyzing the gravitational interaction for the D4-branes in the background
of the NS5-branes, the phase structures in different regions of the parameter
space were studied in the context of classical string theory. In this paper, by
adding the orientifold 4-plane and 6-plane to the above brane configuration, we
describe the intersecting brane configurations of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua of these gauge
theories.Comment: 21 pp, 6 figures; reduced bytes of figures, DBI action analysis added
and to appear in JHE

### On the perturbative expansion of boundary reflection factors of the supersymmetric sinh-Gordon model

The supersymmetric sinh-Gordon model on a half-line with integrable boundary
conditions is considered perturbatively to verify conjectured exact reflection
factors to one loop order. Propagators for the boson and fermion fields
restricted to a half-line contain several novel features and are developed as
prerequisites for the calculations.Comment: 19 pages, 2 figure

### Channel flows of granular materials and their rheological implications

While the flow of a dry granular material down an inclined channel may seem at first sight to be a relatively simple flow, the experiments which have been conducted up to now suggest sufficient complexity which may be present in all but the very simplest granular material flows; consequently it is important to our general understanding of granular material rheology that these experimental observations be fully understood. This review of the current knowledge of channel flows will focus on the basic mechanics of these flows and the contributions the observations have made to an understanding of the rheology. In order to make progress in this objective, it is necessary to avoid some of the complications which can occur in practice. Thus we shall focus only on those flows in which the interstitial fluid plays very little role in determining the rheology. In his classic paper, Bagnold (1954) was able to show that the regime in which the rheology was dominated by particle/particle or particle/wall interactions and in which the viscous stresses in the interstitial fluid played a negligible role could be defined by a single, Reynolds-number-like parameter. It transpires that the important component in this parameter is a number which we shall call the Bagnold number, Ba, defined by Ba = pâ‚ˆdÂ²Î´/ÂµF where pâ‚ˆ,ÂµF are the particle density and interstitial fluid viscosity, d is the particle diameter and Î´ is the principal velocity gradient in the flow. In the shear flows explored by Bagnold Î´ is the shear rate. Bagnold (1954) found that when Ba was greater than about 450 the rheology was dominated by particle/particle and particle/wall collisions. On the other hand, for Ba < 40, the viscosity of the interstitial fluid played the dominant role. More recently Zeininger and Brennen (1985) showed that the same criteria were applicable to the extensional flows in hoppers provided the extensional velocity gradient was used for Î´. This review will focus on the simpler flows at large Ba where the interstitial fluid effects are small.
Other important ancillary effects can be caused by electrical charge separation between the particles or between the particles and the boundary walls. Such effects can be essential in some flows such as those in electrostatic copying machines. Most experimenters have observed electrical effects in granular material flows, particularly when metal components of the structure are not properly grounded. The effect of such electrical forces on the rheology of the flow is a largely unexplored area of research. The lack of discussion of these effects in
this review should not be interpreted as a dismissal of their importance.
Apart from electrical and interstitial fluid effects, this review will also neglect the effects caused by non-uniformities in the size and shape of the particles. Thus, for the most part, we focus on flows of particles of spherical shape and uniform size. It is clear that while an understanding of all of these effects will be necessary in the long term, there remain some important issues which need to be resolved for even the simplest granular material flows

### Geometrically Induced Phase Transitions at Large N

Utilizing the large N dual description of a metastable system of branes and
anti-branes wrapping rigid homologous S^2's in a non-compact Calabi-Yau
threefold, we study phase transitions induced by changing the positions of the
S^2's. At leading order in 1/N the effective potential for this system is
computed by the planar limit of an auxiliary matrix model. Beginning at the two
loop correction, the degenerate vacuum energy density of the discrete confining
vacua split, and a potential is generated for the axion. Changing the relative
positions of the S^2's causes discrete jumps in the energetically preferred
confining vacuum and can also obstruct direct brane/anti-brane annihilation
processes. The branes must hop to nearby S^2's before annihilating, thus
significantly increasing the lifetime of the corresponding non-supersymmetric
vacua. We also speculate that misaligned metastable glueball phases may
generate a repulsive inter-brane force which stabilizes the radial mode present
in compact Calabi-Yau threefolds.Comment: 47 pages, 7 figure

### Supersymmetry Breaking Vacua from M Theory Fivebranes

We consider intersecting brane configurations realizing N=2 supersymmetric
gauge theories broken to N=1 by multitrace superpotentials, and softly to N=0.
We analyze, in the framework of M5-brane wrapping a curve, the supersymmetric
vacua and the analogs of spontaneous supersymmetry breaking and soft
supersymmetry breaking in gauge theories. We show that the M5-brane does not
exhibit the analog of metastable spontaneous supersymmetry breaking, and does
not have non-holomorphic minimal volume curves with holomorphic boundary
conditions. However, we find that any point in the N=2 moduli space can be
rotated to a non-holomorphic minimal volume curve, whose boundary conditions
break supersymmetry. We interpret these as the analogs of soft supersymmetry
breaking vacua in the gauge theory.Comment: 32 pages, 8 figures, harvmac; v2: corrections in eq. 3.6 and in
section 6, reference adde

### Supersymmetric Reflection Matrices

We briefly review the general structure of integrable particle theories in
1+1 dimensions having N=1 supersymmetry. Examples are specific perturbed
superconformal field theories (of Yang-Lee type) and the N=1 supersymmetric
sine-Gordon theory. We comment on the modifications that are required when the
N=1 supersymmetry algebra contains non-trivial topological charges.Comment: 7 pages, Revtex, 2 figures, talk given at the International Seminar
on Supersymmetry and Quantum Field Theory, dedicated to the memory of
D.V.Volkov, Kharkov (Ukraine), January 5-7, 199

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