196 research outputs found
An Algorithm to Generate Classical Solutions for String Effective Action
It is shown explicitly, that a number of solutions for the background field
equations of the string effective action in space-time dimension D can be
generated from any known lower dimensional solution, when background fields
have only time dependence. An application of the result to the two dimensional
charged black hole is presented. The case of background with more general
coordinate dependence is also discussed.Comment: 12 page
Symmetries of String Effective Action and Space-Time Geometry
Two dimensional charged black hole solution is obtained by implementing an
transformation on the three dimensional black string solution. Two
different monopole backgrounds in five dimensions are related through an
transformation. It has been shown in these examples that the
particular transformation corresponds to duality transformation.Comment: 14 page
String Effective Action and Two Dimensional Charged Black Hole
Graviton-dilaton background field equations in three space-time dimensions,
following from the string effective action are solved when the metric has only
time dependence. By taking one of the two space dimensions as compact, our
solution reproduces a recently discovered charged black hole solution in two
space-time dimensions. Solutions in presence of nonvanishing three dimensional
background antisymmetric tensor field are also discussed.Comment: 11 page
Non-canonical folding of Dynkin diagrams and reduction of affine Toda theories
The equation of motion of affine Toda field theory is a coupled equation for
fields, is the rank of the underlying Lie algebra. Most of the theories
admit reduction, in which the equation is satisfied by fewer than fields.
The reductions in the existing literature are achieved by identifying (folding)
the points in the Dynkin diagrams which are connected by symmetry
(automorphism). In this paper we present many new reductions. In other words
the symmetry of affine Dynkin diagrams could be extended and it leads to
non-canonical foldings. We investigate these reductions in detail and formulate
general rules for possible reductions. We will show that eventually most of the
theories end up in that is the theory cannot have a further
dimension reduction where .Comment: 26 pages, Latex2e, usepackage `graphics.sty', 15 figure
Instability of Solitons in imaginary coupling affine Toda Field Theory
Affine Toda field theory with a pure imaginary coupling constant is a
non-hermitian theory. Therefore the solutions of the equation of motion are
complex. However, in dimensions it has many soliton solutions with
remarkable properties, such as real total energy/momentum and mass. Several
authors calculated quantum mass corrections of the solitons by claiming these
solitons are stable. We show that there exists a large class of classical
solutions which develops singularity after a finite lapse of time. Stability
claims, in earlier literature, were made ignoring these solutions. Therefore we
believe that a formulation of quantum theory on a firmer basis is necessary in
general and for the quantum mass corrections of solitons, in particular.Comment: 17 pages, latex, no figure
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