262 research outputs found

### Exactly solvable charged dilaton gravity theories in two dimensions

We find exactly solvable dilaton gravity theories containing a U(1) gauge
field in two dimensional space-time. The classical general solutions for the
gravity sector (the metric plus the dilaton field) of the theories coupled to a
massless complex scalar field are obtained in terms of the stress-energy tensor
and the U(1) current of the scalar field. We discuss issues that arise when we
attempt to use these models for the study of the gravitational back-reaction.Comment: The introductory part is changed. a version to appear in Class.
Quant. Grav. 6 pages, RevTe

### Particle dynamics in a class of 2-dimensional gravity theories

We provide a method to determine the motion of a classical massive particle
in a background geometry of 2-dimensional gravity theories, for which the
Birkhoff theorem holds. In particular, we get the particle trajectory in a
continuous class of 2-dimensional dilaton gravity theories that includes the
Callan-Giddings-Harvey-Strominger (CGHS) model, the Jackiw-Teitelboim (JT)
model, and the $d$-dimensional $s$-wave Einstein gravity. The explicit
trajectory expressions for these theories are given along with the discussions
on the results.Comment: 15 pages, LaTeX. The deletion of the repeated portion of the abstract
and the proper line wrapping of the tex file. No other change

### General Static Solutions of 2-dimensional Einstein-Dilaton-Maxwell-Scalar Theories

General static solutions of effectively 2-dimensional
Einstein-Dilaton-Maxwell-Scalar theories are obtained. Our model action
includes a class of 2-d dilaton gravity theories coupled with a $U(1)$ gauge
field and a massless scalar field. Therefore it also describes the spherically
symmetric reduction of $d$-dimensional Einstein-Scalar-Maxwell theories. The
properties of the analytic solutions are briefly discussed.Comment: 16 pages, Latex fil

### U(N) Instantons on N=1/2 superspace -- exact solution & geometry of moduli space

We construct the exact solution of one (anti)instanton in N=1/2 super
Yang-Mills theory defined on non(anti)commutative superspace. We first identify
N = 1/2 superconformal invariance as maximal spacetime symmetry. For gauge
group U(2), SU(2) part of the solution is given by the standard
(anti)instanton, but U(1) field strength also turns out nonzero. The solution
is SO(4) rotationally symmetric. For gauge group U(N), in contrast to the U(2)
case, we show that the entire U(N) part of the solution is deformed by
non(anti)commutativity and fermion zero-modes. The solution is no longer
rotationally symmetric; it is polarized into an axially symmetric configuration
because of the underlying non(anti)commutativity. We compute the `information
metric' of one (anti) instanton. We find that moduli space geometry is deformed
from hyperbolic space (Euclidean anti-de Sitter space) in a way anticipated
from reduced spacetime symmetry. Remarkably, the volume measure of the moduli
space turns out to be independent of the non(anti)commutativity. Implications
to D-branes in Ramond- Ramond flux background and Maldacena's gauge-gravity
correspondence are discussed.Comment: 39 pages, 3 figures, JHEP style; v2. typos corrected + a paragraph
adde

### Interacting Dipoles from Matrix Formulation of Noncommutative Gauge Theories

We study the IR behavior of noncommutative gauge theory in the matrix
formulation. We find that in this approach, the nature of the UV/IR mixing is
easily understood, which allows us to perform a reliable calculation of the
quantum effective action for the long wavelength modes of the noncommutative
gauge field. At one loop, we find that our description is weakly coupled only
in the supersymmetric theory. At two loops, we find non-trivial interaction
terms suggestive of dipole degrees of freedom. These dipoles exhibit a channel
duality reminiscent of string theory.Comment: LaTeX 11 pages, 4 figures; v.2 minor changes and some references
added; v.3 many more technical details added and significantly different
presentation, use REVTeX 4, to appear in PR

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