279 research outputs found
D-branes in Massive IIA and Solitons in Chern-Simons Theory
We investigate D2-branes and D4-branes parallel to D8-branes. The low energy
world volume theory on the branes is non-supersymmetric Chern-Simons theory. We
identify the fundamental strings as the anyons of the 2+1 Chern-Simons theory
and the D0-branes as solitons. The Chern-Simons theory with a boundary is
modeled using NS 5-branes with ending D6-branes. The brane set-up provides for
a graphical description of anomaly inflow. We also model the 4+1 Chern-Simons
theory using branes and conjecture that D4-branes with a boundary describes a
supersymmetric version of Kaplan's theory of chiral fermions.Comment: 22 pages, 4 figures, harvmac, epsf, references added, sec 4.2 adde
Type IIA Superstrings, Chiral Symmetry, and N=1 4D Gauge Theory Dualities
We study N=1 four dimensional gauge theories as the world volume theory of
D4-branes between NS 5-branes. We find constructions for a number of known
field theory dualities involving groups, coupled by
matter fields F in the representation, in terms of branes of
type IIA string theory. The dual gauge group follows from simply reversing the
ordering of the NS 5-branes and the D6-branes while conserving magnetic charge
on the world volume of the branes. We interpret many field theory phenomena
such as deformation of the superpotential W = \Tr (F\tilde F)^{k+1} in terms
of the position of branes. By looking to D-branes for guidance, we find new N=1
dualities involving arbitrary numbers of gauge groups. We propose a mechanism
for enhanced chiral symmetry in the brane construction which, we conjecture, is
associated with tensionless threebranes in six dimensions.Comment: 32 pages, 9 figures, uses harvmac, tables, and eps
Exact Solutions of Exceptional Gauge Theories from Toric Geometry
We derive four dimensional gauge theories with exceptional groups ,
, , and with matter, by starting from the duality between the
heterotic string on and F-theory on a elliptically fibered Calabi-Yau
3-fold. This configuration is compactified to four dimensions on a torus, and
by employing toric geometry, we compute the type IIB mirrors of the Calabi-Yaus
of the type IIA string theory. We identify the Seiberg-Witten curves describing
the gauge theories as ALE spaces fibered over a base.Comment: 18 pages, 5 figures, uses harvmac and eps
Two Dimensional Mirror Symmetry From M-theory
We construct two dimensional gauge theories with supersymmetry
from branes of type IIA string theory. Quantum effects in the two dimensional
gauge theory are analyzed by embedding the IIA brane construction into
M-theory. We find that the Coulomb branch of one theory and the Higgs branch of
a mirror theory become equivalent at strong coupling. A relationship to the
decoupling limit of the type IIA and IIB 5-branes in Matrix theory is shown.
T-duality between the ALE metric and the wormhole metric of Callan, Harvey, and
Strominger is discussed from a brane perspective and some puzzles regarding
string duality resolved. We comment on the existence of a quantum Higgs branch
in two dimensional theories. Branes prove to be useful tools in analyzing
singular conformal field theories.Comment: 21 pages, 3 figures, uses harvmac and eps
Patterns of Duality in N=1 SUSY Gauge Theories
We study the patterns in the duality of a wide class of N=1 supersymmetric
gauge theories in four dimensions. We present many new generalizations of the
classic duality models of Kutasov and Schwimmer, which have themselves been
generalized numerous times in works of Intriligator, Leigh and the present
authors. All of these models contain one or two fields in a two-index tensor
representation, along with fields in the defining representation. The
superpotential for the two-index tensor(s) resembles A_k or D_k singularity
forms, generalized from numbers to matrices. Looking at the ensemble of these
models, classifying them by superpotential, gauge group, and ``level'' -- for
terminology we appeal to the architecture of a typical European-style theatre
-- we identify emerging patterns and note numerous interesting puzzles.Comment: 34 pages, 4 figures, uses harvmac and table
The Age Difference between the Globular Cluster Sub-populations in NGC 4472
The age difference between the two main globular cluster sub-populations in
the Virgo giant elliptical galaxy, NGC 4472 (M 49), has been determined using
HST WFPC2 images in the F555W and F814W filters. Accurate photometry has been
obtained for several hundred globular clusters in each of the two main
sub-populations, down to more than one magnitude below the turn-over of their
luminosity functions. This allows precise determinations of both the mean
colors and the turn-over magnitudes of the two main sub-populations. By
comparing the data with various population synthesis models, the
age-metallicity pairs that fit both the observed colors and magnitudes have
been identified. The metal-poor and the metal-rich globular clusters are found
to be coeval within the errors ( Gyr). If one accepts the validity of
our assumptions, these errors are dominated by model uncertainties. A
systematic error of up to 4 Gyr could affect this result if the blue and the
red clusters have significantly different mass distributions. However, that one
sub-population is half as old as the other is excluded at the 99% confidence
level. The different globular cluster populations are assumed to trace the
galaxy's major star-formation episodes. Consequently, the vast majority of
globular clusters, and by implication the majority of stars, in NGC 4472 formed
at high redshifts but by two distinct mechanisms or in two episodes.Comment: 32 pages, including 12 postscript figures, accepted for publication
in the Astronomical Journal, December 1999 issu
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