34,308 research outputs found
Simple Current Actions of Cyclic Groups
Permutation actions of simple currents on the primaries of a Rational
Conformal Field Theory are considered in the framework of admissible weighted
permutation actions. The solution of admissibility conditions is presented for
cyclic quadratic groups: an irreducible WPA corresponds to each subgroup of the
quadratic group. As a consequence, the primaries of a RCFT with an order n
integral or half-integral spin simple current may be arranged into multiplets
of length k^2 (where k is a divisor of n) or 3k^2 if the spin of the simple
current is half-integral and k is odd.Comment: Added reference, minor change
D-brane conformal field theory
We outline the structure of boundary conditions in conformal field theory. A
boundary condition is specified by a consistent collection of reflection
coefficients for bulk fields on the disk together with a choice of an
automorphism \omega of the fusion rules that preserves conformal weights.
Non-trivial automorphisms \omega correspond to D-brane configurations for
arbitrary conformal field theories.Comment: 7 pages, LaTeX2e. Slightly extended version of a talk given by J.
Fuchs at the 31st International Symposium Ahrenshoop on the Theory of
Elementary Particles, Buckow, Germany, September 199
Conformal field theory, boundary conditions and applications to string theory
This is an introduction to two-dimensional conformal field theory and its
applications in string theory. Modern concepts of conformal field theory are
explained, and it is outlined how they are used in recent studies of D-branes
in the strong curvature regime by means of CFT on surfaces with boundary.Comment: 45 pages, LaTeX2
The action of outer automorphisms on bundles of chiral blocks
On the bundles of WZW chiral blocks over the moduli space of a punctured
rational curve we construct isomorphisms that implement the action of outer
automorphisms of the underlying affine Lie algebra. These bundle-isomorphisms
respect the Knizhnik-Zamolodchikov connection and have finite order. When all
primary fields are fixed points, the isomorphisms are endomorphisms; in this
case, the bundle of chiral blocks is typically a reducible vector bundle. A
conjecture for the trace of such endomorphisms is presented; the proposed
relation generalizes the Verlinde formula. Our results have applications to
conformal field theories based on non-simply connected groups and to the
classification of boundary conditions in such theories.Comment: 46 pages, LaTeX2e. Final version (Commun.Math.Phys., in press). We
have implemented the fact that the group of automorphisms in general acts
only projectively on the chiral blocks and corrected some typo
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