17 research outputs found
Holography, Singularities on Orbifolds and 4D N=2 SQCD
Type II string theory compactified on a Calabi-Yau manifold, with a
singularity modeled by a hypersurface in an orbifold, is considered. In the
limit of vanishing string coupling, one expects a non gravitational theory
concentrated at the singularity. It is proposed that this theory is
holographicly dual to a family of ``non-critical'' superstring vacua,
generalizing a previous proposal for hypersurfaces in flat space. It is argued
that a class of such singularities is relevant for the study of non-trivial IR
fixed points that appear in the moduli space of four-dimensional N=2 SQCD:
SU(N_c) gauge theory with matter in the fundamental representation. This
includes the origin in the moduli space of the SU(N_c) gauge theory with
N_f=2N_c fundamentals. The 4D IR fixed points are studied using the
anti-holographic description and the results agree with information available
from gauge theory.Comment: 33 pages (Latex
On the Quantization Constraints for a D3 Brane in the Geometry of NS5 Branes
A D3 brane in the background of NS5 branes is studied semi-classically. The
conditions for preserved supersymmetry are derived, leading to a differential
equation for the shape of the D3 brane. The solutions of this equation are
analyzed. For a D3 brane intersecting the NS5 branes, the angle of approach is
known to be restricted to discrete values. Four different ways to obtain this
quantization are described. In particular, it is shown that, assuming the D3
brane avoids intersecting a {\em single} NS5 brane, the above discrete values
correspond to the different possible positions of the D3 branes among the NS5
branes.Comment: 25 pages (plain LaTeX) and 4 figures (encapsulated postscript
A New Family of Solvable Self-Dual Lie Algebras
A family of solvable self-dual Lie algebras is presented. There exist a few
methods for the construction of non-reductive self-dual Lie algebras: an
orthogonal direct product, a double-extension of an Abelian algebra, and a
Wigner contraction. It is shown that the presented algebras cannot be obtained
by these methods.Comment: LaTeX, 12 page
Construction of a Complete Set of States in Relativistic Scattering Theory
The space of physical states in relativistic scattering theory is
constructed, using a rigorous version of the Dirac formalism, where the Hilbert
space structure is extended to a Gel'fand triple. This extension enables the
construction of ``a complete set of states'', the basic concept of the original
Dirac formalism, also in the cases of unbounded operators and continuous
spectra. We construct explicitly the Gel'fand triple and a complete set of
``plane waves'' -- momentum eigenstates -- using the group of space-time
symmetries. This construction is used (in a separate article) to prove a
generalization of the Coleman-Mandula theorem to higher dimension.Comment: 30 pages, Late
Aspects of Confinement and Screening in M theory
Confinement and Screening are investigated in SUSY gauge theories, realized
by an M5 brane configuration, extending an approach applied previously to N=1
SYM theory, to other models. The electric flux tubes are identified as M2
branes ending on the M5 branes and the conserved charge they carry is
identified as a topological property. The group of charges carried by the flux
tubes is calculated and the results agree in all cases considered with the
field theoretical expectations. In particular, whenever the dynamical matter is
expected to screen the confining force, this is reproduced correctly in the M
theory realization.Comment: 26 pages (LaTeX) + 9 figures (encapsulated postscript); ver.2:
references adde
WZNW Models and Gauged WZNW Models Based on a Family of Solvable Lie Algebras
A family of solvable self-dual Lie algebras that are not double extensions of
Abelian algebras and, therefore, cannot be obtained through a Wigner
contraction, is presented. We construct WZNW and gauged WZNW models based on
the first two algebras in this family. We also analyze some general phenomena
arising in such models.Comment: 48 pages, LaTeX, no figure
The Coulomb Phase in N=1 Gauge Theories With a LG-Type Superpotenetial
We consider N=1 supersymmetric gauge theories with a simple classical gauge
group, one adjoint pairs () of (fundamental,
anti-fundamental) and a tree-level superpotential with terms of the
Landau-Ginzburg form . The quantum moduli space of these
models includes a Coulomb branch. We find hyperelliptic curves that encode the
low energy effective gauge coupling for the groups SO(N_c) and USp(N_c) (the
corresponding curve for SU(N_c) is already known). As a consistency check, we
derive the sub-space of some vacua with massless dyons via confining phase
superpotentials. We also discuss the existence and nature of the non-trivial
superconformal points appearing when singularities merge in the Coulomb branch.Comment: 26 pages, latex, no figures; the derivation of the classical part of
the curves is clarified; version published in Nucl.Phys.
The D2-D6 System and a Fibered AdS Geometry
The system of D2 branes localized on or near D6 branes is considered. The
world-volume theory on the D2 branes is investigated, using its conjectured
relation to the near-horizon geometry. The results are in agreement with known
facts and expectations for the corresponding field theory and a rich phase
structure is obtained as a function of the energy scale and the number of
branes. In particular, for an intermediate range of the number of D6 branes,
the IR geometry is that of an AdS_4 space fibered over a compact space. This
D2-D6 system is compared to other systems, related to it by compactification
and duality and it is shown that the qualitative differences have compatible
explanations in the geometric and field-theoretic descriptions. Another system
-- that of NS5 branes located at D6 branes -- is also briefly studied, leading
to a similar phase structure.Comment: 35 pages (Latex) and 2 figures (encapsulated postscript). Ver2: added
discussion of the relation to the system without D6 branes (in the
introduction and in figure 1); added description of the geometrical
realization of the R symmetries (in section 3.1