1,154 research outputs found
Gauss Decomposition, Wakimoto Realisation and Gauged WZNW Models
The implications of gauging the Wess-Zumino-Novikov-Witten (WZNW) model using
the Gauss decomposition of the group elements are explored. We show that,
contrary to standard gauging of WZNW models, this gauging is carried out by
minimally coupling the gauge fields. We find that this gauging, in the case of
gauging an abelian vector subgroup, differs from the standard one by terms
proportional to the field strength of the gauge fields. We prove that gauging
an abelian vector subgroup does not have a nonlinear sigma model
interpretation. This is because the target-space metric resulting from the
integration over the gauge fields is degenerate. We demonstrate, however, that
this kind of gauging has a natural interpretation in terms of Wakimoto
variables.Comment: 17 pages, BONN-HE-93-4
WZNW Models from Non-Standard Bilinear Forms
We study the WZNW models based on nonstandard bilinear forms. We approach the
problem from algebraic, perturbative and functional exact methods. It is shown
that even in the case of integer we can find irrational CFT's. We prove
that when the base group is noncompact with nonabelian maximal compact
subgroup, the Kac-Moody representations are nonunitary.Comment: LaTeX file, 26 page
Nilpotent Gauging of SL(2,R) models, and Liouville Field
We consider the gauging of WZNW model by its nilpotent subgroup
E(1). The resulting space-time of the corresponding sigma model is seen to
collapse to a one dimensional field theory of Liouville. Gauging the diagonal
subgroup of theory yields an
extremal three dimensional black string. We show that these solutions are
obtained from the two dimensional black hole of Witten and the three
dimensional black string of Horne and Horowitz by boosting the gauge group.Comment: 17 pages, late
Distributed Systems of Intersecting Branes at Arbitrary Angles
A `reduced' action formulation for a general class of the supergravity
solutions, corresponding to the `marginally' bound `distributed' systems of
various types of branes at arbitrary angles, is developed. It turns out that
all the information regarding the classical features of such solutions is
encoded in a first order Lagrangian (the `reduced' Lagrangian) corresponding to
the desired geometry of branes. The marginal solution for a system of such
distributions (for various distribution functions) span an dimensional
submanifold of the fields' configuration (target) space, parametrised by a set
of independent harmonic functions on the transverse space. This
submanifold, which we call it as the `-surface', is a null surface with
respect to a metric on the configuration space, which is defined by the reduced
Lagrangian. The equations of motion then transform to a set of equations
describing the embedding of a null geodesic surface in this space, which is
identified as the -surface. Using these facts, we present a very simple
derivation of the conventional orthogonal solutions together with their
intersection rules. Then a new solution for a (distributed) pair of -branes
at SU(2) angles in dimensions is derived.Comment: Latex file, 58 pages, no figures, 5 tables, This revision contains
some minor changes of the original version including those of the title,
abstract and referrences. Some comments are adde
Different D-brane Interactions
We use rotation of one D-brane with respect to the other to reveal the hidden
structure of D-branes in type-II theories. This is done by calculation of the
interaction amplitude for two different parallel and angled branes. The
analysis of strings with different boundary conditions at the ends is also
given. The stable configuration for two similar branes occurs when they are
anti-parallel. For branes of different dimensions stability is attained for
either parallel or anti-parallel configurations and when dimensions differ by
four the amplitude vanishes at the stable point. The results serve as more
evidence that D-branes are stringy descriptions of non-perturbative extended
solutions of SUGRA theories, as low energy approximation of superstrings.Comment: Tex, 12 pages. Typographical errors are corrected, minor changes
done, acknowledgements adde
Two Moving-Angled 1-Branes with Electric Fields in a Partially Compact Spacetime
In this article we consider two -branes at angle in the presence of the
background electric fields, in a partially compact spacetime. The branes have
motions along a common direction that is perpendicular to both of them. Using
the boundary state formalism, we calculate their interaction amplitude. Some
special cases of this interaction will be studied in detail.Comment: 10 pages, no figure, Late
Mixed Boundary Conditions and Brane-String Bound States
In this article we consider open strings with mixed boundary conditions (a
combination of Neumann and Dirichlet conditions at each end). We discuss how
their end points show a -brane with NS-NS charge, i.e. a bound state of a
D-brane with a fundamental strings. We show that these branes are BPS
saturated. In the case of one-branes, we show that their mass densities are in
agreement with IIb SUGRA which is Sl(2,Z) invariant. Using Chan-Paton factors,
we extend our results to the case of bound states of D-strings and
F-strings. These string theoretic results are also checked in the effective
field theory limit.Comment: Latex file, 20 pages, No Figures, some paragraphs adde
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