2,417 research outputs found
Hamiltonian formulation of nonAbelian noncommutative gauge theories
We implement the Hamiltonian treatment of a nonAbelian noncommutative gauge
theory, considering with some detail the algebraic structure of the
noncommutative symmetry group. The first class constraints and Hamiltonian are
obtained and their algebra derived, as well as the form of the gauge invariance
they impose on the first order action.Comment: enlarged version, 7 pages, RevTe
Diffeomorphism, kappa transformations and the theory of non-linear realisations
We will show how the theory of non-linear realisations can be used to
naturally incorporate world line diffeomorphisms and kappa transformations for
the point particle and superpoint particle respectively. Similar results also
hold for a general p-brane and super p-brane, however, we must in these cases
include an additional Lorentz transformation.Comment: 19pages, no figure. References are added and typos are correcte
BIons in topological string theory
When many fundamental strings are stacked together, they puff up into
D-branes. BIons and giant gravitons are the examples of such D-brane
configurations that arise from coincident strings. We propose and demonstrate
analogous transitions in topological string theory. Such transitions can also
be understood in terms of the Fourier transform of D-brane amplitudes.Comment: 21 pages; v.2 references added; v.3 reference added; v.4 minor
corrections; v.5 substantial rewritin
A Note on Unitarity of Non-Relativistic Non-Commutative Theories
We analyze the unitarity of a non-relativistic non-commutative scalar field
theory. We show that electric backgrounds spoil unitarity while magnetic ones
do not. Furthermore, unlike its relativistic counterparts, unitarity can not be
restored (at least at the level of one-to-one scattering amplitude) by adding
new states to the theory. This is a signal that the model cannot be embedded in
a natural way in string theory.Comment: 6 pages, 2 figures. References adde
A prediction for bubbling geometries
We study the supersymmetric circular Wilson loops in N=4 Yang-Mills theory.
Their vacuum expectation values are computed in the parameter region that
admits smooth bubbling geometry duals. The results are a prediction for the
supergravity action evaluated on the bubbling geometries for Wilson loops.Comment: 21 pages, latex; v.2 reference added; v.3 minor correction
D-branes as a Bubbling Calabi-Yau
We prove that the open topological string partition function on a D-brane
configuration in a Calabi-Yau manifold X takes the form of a closed topological
string partition function on a different Calabi-Yau manifold X_b. This
identification shows that the physics of D-branes in an arbitrary background X
of topological string theory can be described either by open+closed string
theory in X or by closed string theory in X_b. The physical interpretation of
the ''bubbling'' Calabi-Yau X_b is as the space obtained by letting the
D-branes in X undergo a geometric transition. This implies, in particular, that
the partition function of closed topological string theory on certain bubbling
Calabi-Yau manifolds are invariants of knots in the three-sphere.Comment: 32 pages; v.2 reference adde
Holographic Gauge Theories in Background Fields and Surface Operators
We construct a new class of supersymmetric surface operators in N=4 SYM and
find the corresponding dual supergravity solutions. We show that the insertion
of the surface operator - which is given by a WZW model supported on the
surface - appears by integrating out the localized degrees of freedom along the
surface which arise microscopically from a D3/D7 brane intersection.
Consistency requires constructing N=4 SYM in the D7 supergravity background and
not in flat space. This enlarges the class of holographic gauge theories dual
to string theory backgrounds to gauge theories in non-trivial supergravity
backgrounds. The dual Type IIB supergravity solutions we find reveal - among
other features - that the holographic dual gauge theory does indeed live in the
D7-brane background.Comment: 42 pages, harvmac, corrected typo
Wilson Loops, Geometric Transitions and Bubbling Calabi-Yau's
Motivated by recent developments in the AdS/CFT correspondence, we provide
several alternative bulk descriptions of an arbitrary Wilson loop operator in
Chern-Simons theory. Wilson loop operators in Chern-Simons theory can be given
a description in terms of a configuration of branes or alternatively
anti-branes in the resolved conifold geometry. The representation of the Wilson
loop is encoded in the holonomy of the gauge field living on the dual brane
configuration. By letting the branes undergo a new type of geometric
transition, we argue that each Wilson loop operator can also be described by a
bubbling Calabi-Yau geometry, whose topology encodes the representation of the
Wilson loop. These Calabi-Yau manifolds provide a novel representation of knot
invariants. For the unknot we confirm these identifications to all orders in
the genus expansion.Comment: 26 pages; v.2 typos corrected, explanations clarified; v.3 typos
corrected, reference adde
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