113 research outputs found
A remark on T-duality and quantum volumes of zero-brane moduli spaces
T-duality (Fourier-Mukai duality) and properties of classical instanton
moduli spaces can be used to deduce some properties of
-corrected moduli spaces of branes for Type IIA string theory
compactified on or . Some interesting differences between the two
compactifications are exhibited.Comment: 6-pages, Harvmac big, 2 figures; version 2 : ref added v3 : final
JHEP version - minor clarification + ref adde
Zero-Branes on a Compact Orbifold
The non-commutative algebra which defines the theory of zero-branes on
allows a unified description of moduli spaces associated with
zero-branes, two-branes and four-branes on the orbifold space. Bundles on a
dual space play an important role in this description. We
discuss these moduli spaces in the context of dualities of K3
compactifications, and in terms of properties of instantons on .
Zero-branes on the degenerate limits of the compact orbifold lead to fixed
points with six-dimensional scale but not conformal invariance. We identify
some of these in terms of the ADS dual of the theory at large ,
giving evidence for an interesting picture of "where the branes live" in ADS.Comment: 34 pages (harvmac big); version to appear in JHE
Non commutative gravity from the ADS/CFT correspondence
The exclusion principle of Maldacena and Strominger is seen to follow from
deformed Heisenberg algebras associated with the chiral rings of S_N orbifold
CFTs. These deformed algebras are related to quantum groups at roots of unity,
and are interpreted as algebras of space-time field creation and annihilation
operators. We also propose, as space-time origin of the stringy exclusion
principle, that the space-time of the associated
six-dimensional supergravity theory acquires, when quantum effects are taken
into account, a non-commutative structure given by .
Both remarks imply that finite N effects are captured by quantum groups
with . This implies that a proper
framework for the theories in question is given by gravity on a non-commutative
spacetime with a q-deformation of field oscillators. An interesting consequence
of this framework is a holographic interpretation for a product structure in
the space of all unitary representations of the non-compact quantum group
at roots of unity.Comment: 28 pages in harvmac big ; v2: Minor corrections, ref adde
Wilson Loops in 2D Yang Mills: Euler characters and Loop equations
We give a simple diagrammatic algorithm for writing the chiral large
expansion of intersecting Wilson loops in and Yang Mills
theory in terms of symmetric groups, generalizing the result of Gross and
Taylor for partition functions. We prove that these expansions compute Euler
characters of a space of holomorphic maps from string worldsheets with
boundaries. We prove that the Migdal-Makeenko equations hold for the chiral
theory and show that they can be expressed as linear constraints on
perturbations of the chiral partition functions. We briefly discuss
finite , the non-chiral expansion, and higher dimensional lattice models.Comment: 55 pages, harvmac, 35 figure
Large N 2D Yang-Mills Theory and Topological String Theory
We describe a topological string theory which reproduces many aspects of the
1/N expansion of SU(N) Yang-Mills theory in two spacetime dimensions in the
zero coupling (A=0) limit. The string theory is a modified version of
topological gravity coupled to a topological sigma model with spacetime as
target. The derivation of the string theory relies on a new interpretation of
Gross and Taylor's ``\Omega^{-1} points.'' We describe how inclusion of the
area, coupling of chiral sectors, and Wilson loop expectation values can be
incorporated in the topological string approach.Comment: 95 pages, 15 Postscript figures, uses harvmac (Please use the "large"
print option.) Extensive revisions of the sections on topological field
theory. Added a compact synopsis of topological field theory. Minor typos
corrected. References adde
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