91 research outputs found
Duality Transformations Away From Conformal Points
Target space duality transformations are considered for bosonic sigma models
and strings away from RG fixed points. A set of consistency conditions are
derived, and are seen to be nontrivially satisfied at one-loop order for
arbitrary running metric, antisymmetric tensor and dilaton backgrounds. Such
conditions are sufficiently stringent to enable an independent determination of
the sigma model beta functions at this order.Comment: 11 pages, plain TeX. Uses harvmac.te
Duality, Quotients, and Currents
We study the generalization of duality to arbitrary conformally
invariant sigma models with an isometry. We show that any pair of dual sigma
models can be represented as quotients of a self-dual sigma model obtained by
gauging different combinations of chiral currents. This observation is used to
clarify the interpretation of the generalized duality as a symmetry of
conformal field theory. We extend these results to supersymmetric sigma
models.Comment: 20 page
One loop renormalizability of the Poisson-Lie sigma models
We present the proof of the one loop renormalizability in the strict field
theoretic sense of the Poisson-Lie sigma models. The result is valid for any
Drinfeld double and it relies solely on the Poisson-Lie structure encoded in
the target manifold.Comment: 11 page
Poisson-Lie T-duality
A description of dual non-Abelian duality is given, based on the notion of
the Drinfeld double. The presentation basically follows the original paper
\cite{KS2}, written in collaboration with P. \v Severa, but here the emphasis
is put on the algebraic rather than the geometric aspect of the construction
and a concrete example of the Borelian double is worked out in detail.Comment: 11 pages, LaTeX, Lecture given at Trieste conference on S-duality and
mirror symmetry, June 1995, (signs in Eqs. (10,11) corrected, 1 reference
added
Infinity Cancellation, Type I' Compactification and String S-Matrix Functional
Nonvanishing tadpoles and possible infinities associated in the multiparticle
amplitudes are discussed with regard to the disk and diagrams of the
Type I' compactification. We find that the infinity cancellation of
type theory extends to this case as well despite the presence of tadpoles
localized in the D-brane world-volume and the orientifold surfaces. Formalism
of string S-matrix generating functional is presented to find a consistent
string background as c-number source function: we find this only treats the
cancellation of the tadpoles in the linearized approximation. Our formalism
automatically provides representation of the string amplitudes on this
background to all orders in .Comment: 18 pages, Latex, more references adde
A Canonical Approach to Duality Transformations
We show that Buscher's abelian duality transformation rules can be recovered
in a very simple way by performing a canonical transformation first suggested
by Giveon, Rabinovici and Veneziano. We explore the properties of this
transformation, and also discuss some aspects of non-abelian duality.Comment: 11 p, LaTex, preprint CERN-TH-7337/94 (some comments and references
added
A nonlocal Poisson bracket of the sine-Gordon model
It is well known that the classical string on a two-sphere is more or less
equivalent to the sine-Gordon model. We consider the nonabelian dual of the
classical string on a two-sphere. We show that there is a projection map from
the phase space of this model to the phase space of the sine-Gordon model. The
corresponding Poisson structure of the sine-Gordon model is nonlocal with one
integration.Comment: 18 pages, LaTeX, v2,3: added Section 4 and reference
DeWitt-Virasoro construction
We study a particular approach for analyzing worldsheet conformal invariance
for bosonic string propagating in a curved background using hamiltonian
formalism. We work in the Schrodinger picture of a single particle description
of the problem where the particle moves in an infinite-dimensional space.
Background independence is maintained in this approach by adopting DeWitt's
(Phys.Rev.85:653-661,1952) coordinate independent formulation of quantum
mechanics. This enables us to construct certain background independent notion
of Virasoro generators, called DeWitt-Virasoro (DWV) generators, and invariant
matrix elements of an arbitrary operator constructed out of them in spin-zero
representation. We show that the DWV algebra is given by the Witt algebra with
additional anomalous terms that vanish for Ricci-flat backgrounds. The actual
quantum Virasoro generators should be obtained by first introducing the vacuum
state and then normal ordering the DWV generators with respect to that. We
demonstrate the procedure in the simple cases of flat and pp-wave backgrounds.
This is a shorter version of arXiv:0912.3987 [hep-th] with many technical
derivations omitted.Comment: 18 pages, shorter version of arXiv:0912.3987 [hep-th] accepted for
publication in Pramana - Journal of Physic
A Novel Symmetry in Sigma Models
A class of non-linear sigma models possessing a new symmetry is identified.
The same symmetry is also present in Chern-Simons theories. This hints at a
possible topological origin for this class of sigma models. The non-linear
sigma models obtained by non-Abelian duality are a particular case in this
class.Comment: 9 pages, latex, no figure
On the inflationary solutions in higher-derivative gravity with dilaton field
We discuss the existence of de Sitter inflationary solutions for the
string-inspired fourth-derivative gravity theories with dilaton field. We
consider a space-time of arbitrary dimension D and an arbitrary parametrization
of the target space metric. The specific features of the theory in dimension
D=4 and those of the special ghost-free parametrization of the metric are
found. We also consider similar string-inspired theories with torsion and
construct an inflationary solution with torsion and dilaton for D=4. The
stability of the inflationary solutions is also investigated.Comment: 13 pages, LaTeX, no figure
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