5,499 research outputs found
Cohomological Yang-Mills theories on KĂ€hler 3-folds
We study topological gauge theories with Nc = (2; 0) supersymmetry based on stable bundles
on general KĂ€hler 3-folds. In order to have a theory that is well defined and well behaved,
we consider a model based on an extension of the usual holomorphic bundle by including a
holomorphic 3-form. The correlation functions of the model describe complex 3-dimensional
generalizations of Donaldson-Witten type invariants. We show that the path integral can be
written as a sum of contributions from stable bundles and a complex 3-dimensional version
of Seiberg-Witten monopoles. We study certain deformations of the theory, which allow us
to consider the situation of reducible connections. We shortly discuss situations of reduced
holonomy. After dimensional reduction to a KĂ€hler 2-fold, the theory reduces to Vafa-Witten
theory. On a Calabi-Yau 3-fold, the supersymmetry is enhanced to Nc = (2; 2). This model
may be used to describe classical limits of certain compactifications of (matrix) string theory
Models for Bundles on Calabi-Yau: A Proposal for Matrix String Compactifications
We describe a class of supersymmetric gauged linear sigma-model, whose target space is the infinite dimensional space of bundles on a Calabi-Yau 3- or 2-fold. This target space can be considered the configuration space of D-branes wrapped around the Calabi-Yau. We propose that this model can be used to define matrix string theory compactifications. In the infrared limit the model flows to a superconformal non-linear sigma-model whose target space is the moduli space of BPS configurations of branes on the compact space, containing the moduli space of semi-stable bundles. We argue that the bulk degrees of freedom decouple in the infrared limit if semi-stability implies stability. We study topological versions of the model on Calabi-Yau 3-folds. The resulting B-model is argued to be equivalent to the holomorphic Chern-Simons theory proposed by Witten. The A-model and half-twisted model define the quantum cohomology ring and the elliptic genus, respectively, of the moduli space of stable bundles on a Calabi-Yau 3-fold
One-dimensional structures behind twisted and untwisted superYang-Mills theory
We give a one-dimensional interpretation of the four-dimensional twisted N=1
superYang-Mills theory on a Kaehler manifold by performing an appropriate
dimensional reduction. We prove the existence of a 6-generator superalgebra,
which does not possess any invariant Lagrangian but contains two different
subalgebras that determine the twisted and untwisted formulations of the N=1
superYang-Mills theory.Comment: 12 pages. Final version to appear in Lett. Math. Phys. with improved
notation and misprints correcte
Deformation independent open brane metrics and generalized theta parameters
We investigate the consequences of generalizing certain well established
properties of the open string metric to the conjectured open membrane and open
Dp-brane metrics. By imposing deformation independence on these metrics their
functional dependence on the background fields can be determined including the
notorious conformal factor. In analogy with the non-commutativity parameter
in the string case, we also obtain `generalized' theta
parameters which are rank q+1 antisymmetric tensors (polyvectors) for open
Dq-branes and rank 3 for the open membrane case. The expressions we obtain for
the open membrane quantities are expected to be valid for general background
field configurations, while the open D-brane quantities are only valid for one
parameter deformations. By reducing the open membrane data to five dimensions,
we show that they, modulo a subtlety with implications for the relation between
OM-theory and NCYM, correctly generate the open string and open D2-data.Comment: 24 pages, LaTe
Effective descriptions of branes on non-geometric tori
We investigate the low-energy effective description of non-geometric
compactifications constructed by T-dualizing two or three of the directions of
a T^3 with non-vanishing H-flux. Our approach is to introduce a D3-brane in
these geometries and to take an appropriate decoupling limit. In the case of
two T-dualities, we find at low energies a non-commutative T^2 fibered
non-trivially over an S^1. In the UV this theory is still decoupled from
gravity, but is dual to a little string theory with flavor. For the case of
three T-dualities, we do not find a sensible decoupling limit, casting doubt on
this geometry as a low-energy effective notion in critical string theory.
However, by studying a topological toy model in this background, we find a
non-associative geometry similar to one found by Bouwknegt, Hannabuss, and
Mathai.Comment: 22 pages, 4 figures, references adde
Semiclassical strings in AdS(3) X S^2
In this paper, we investigate the semiclassical strings in AdS(3)XS^2, in
which the string configuration of AdS(3) is classified to three cases depending
on the parameters. Each of these has a different anomalous dimension
proportional to logS, S^(1/3) and S, where S is a angular momentum on AdS(3).
Further we generalize the dispersion relations for various string configuration
on AdS(3)XS^2.Comment: 15 pages, added reference
An action principle for Vasiliev's four-dimensional higher-spin gravity
We provide Vasiliev's fully nonlinear equations of motion for bosonic gauge
fields in four spacetime dimensions with an action principle. We first extend
Vasiliev's original system with differential forms in degrees higher than one.
We then derive the resulting duality-extended equations of motion from a
variational principle based on a generalized Hamiltonian sigma-model action.
The generalized Hamiltonian contains two types of interaction freedoms: One set
of functions that appears in the Q-structure of the generalized curvatures of
the odd forms in the duality-extended system; and another set depending on the
Lagrange multipliers, encoding a generalized Poisson structure, i.e. a set of
polyvector fields of ranks two or higher in target space. We find that at least
one of the two sets of interaction-freedom functions must be linear in order to
ensure gauge invariance. We discuss consistent truncations to the minimal Type
A and B models (with only even spins), spectral flows on-shell and provide
boundary conditions on fields and gauge parameters that are compatible with the
variational principle and that make the duality-extended system equivalent, on
shell, to Vasiliev's original system.Comment: 37 pages. References added, corrected typo
On the Open-Closed B-Model
We study the coupling of the closed string to the open string in the
topological B-model. These couplings can be viewed as gauge invariant
observables in the open string field theory, or as deformations of the
differential graded algebra describing the OSFT. This is interpreted as an
intertwining map from the closed string sector to the deformation (Hochschild)
complex of the open string algebra. By an explicit calculation we show that
this map induces an isomorphism of Gerstenhaber algebras on the level of
cohomology. Reversely, this can be used to derive the closed string from the
open string. We shortly comment on generalizations to other models, such as the
A-model.Comment: LaTeX, 48 pages. Citation adde
Centrality dependence of charged hadron transverse momentum spectra in d+Au collisions at sqrt(s_NN) = 200 GeV
We have measured transverse momentum distributions of charged hadrons
produced in d+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were obtained
for transverse momenta 0.25 < p_T < 6.0 GeV/c, in a pseudorapidity range of 0.2
< eta < 1.4 in the deuteron direction. The evolution of the spectra with
collision centrality is presented in comparison to p+pbarcollisions at the same
collision energy. With increasing centrality, the yield at high transverse
momenta increases more rapidly than the overall particle density, leading to a
strong modification of the spectral shape. This change in spectral shape is
qualitatively different from observations in Au+Au collisions at the same
energy. The results provide important information for discriminating between
different models for the suppression of high-p_T hadrons observed in Au+Au
collisions.Comment: 5 pages, 4 figures, submitted to PR
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