19 research outputs found
Asymmetric Cosets
The aim of this work is to present a general theory of coset models G/H in
which different left and right actions of H on G are gauged. Our main results
include a formula for their modular invariant partition function, the
construction of a large set of boundary states and a general description of the
corresponding brane geometries. The paper concludes with some explicit
applications to the base of the conifold and to the time-dependent Nappi-Witten
background.Comment: 34 pages, LaTeX, 8 figures, 1 table, v2: references added, v3: typos
correcte
The diagonal cosets of the Heisenberg group
In this paper we study the diagonal cosets of the non-compact H4 WZW model.
Generalising earlier work by Antoniadis and Obers, we provide an exact
world-sheet description for several families of non-maximally symmetric
gravitational plane waves with background NS fluxes. We show that the
sigma-models that correspond to an asymmetric action of the gauge group
smoothly interpolate between singular and non-singular plane waves. We also
analyse the representations of the coset chiral algebra and derive the spectrum
of all the models.Comment: 42 pages, v2: more explicit expressions for the background fields in
section 3.2.2, reference [49] added, some typos correcte
Generalised permutation branes
We propose a new class of non-factorising D-branes in the product group GxG
where the fluxes and metrics on the two factors do not necessarily coincide.
They generalise the maximally symmetric permutation branes which are known to
exist when the fluxes agree, but break the symmetry down to the diagonal
current algebra in the generic case. Evidence for the existence of these branes
comes from a Lagrangian description for the open string world-sheet and from
effective Dirac-Born-Infeld theory. We state the geometry, gauge fields and, in
the case of SU(2)xSU(2), tensions and partial results on the open string
spectrum. In the latter case the generalised permutation branes provide a
natural and complete explanation for the charges predicted by K-theory
including their torsion.Comment: 33 pages, 6 figures, v2: Extended discussion of K-theory
interpretation of our branes for products of higher rank groups in the
conclusions; v3: Correction of formula (35) and adjustment of the discussion
below equation (45) (no change of result). Footnote 9 points out a previously
unnoticed subtlety and provides a reference to a more detailed discussio
The abelian cosets of the Heisenberg group
In this paper we study the abelian cosets of the H(4) WZW model. They
coincide or are related to several interesting three-dimensional backgrounds
such as the Melvin model, the conical point-particle space-times and the null
orbifold. We perform a detailed CFT analysis of all the models and compute the
coset characters as well as some typical three-point couplings of coset
primaries.Comment: 26 pages; v2: minor typos corrected, also added section 3.3 and 4.3
with a few comments on a third class of geometries that have not been
discussed in v
Non-chiral current algebras for deformed supergroup WZW models
We study deformed WZW models on supergroups with vanishing Killing form. The
deformation is generated by the isotropic current-current perturbation which is
exactly marginal under these assumptions. It breaks half of the global
isometries of the original supergroup. The current corresponding to the
remaining symmetry is conserved but its components are neither holomorphic nor
anti-holomorphic. We obtain the exact two- and three-point functions of this
current and a four-point function in the first two leading orders of a 1/k
expansion but to all orders in the deformation parameter. We further study the
operator product algebra of the currents, the equal time commutators and the
quantum equations of motion. The form of the equations of motion suggests the
existence of non-local charges which generate a Yangian. Possible applications
to string theory on Anti-de Sitter spaces and to condensed matter problems are
briefly discussed.Comment: 43 pages, Latex, one eps figure; v.2: minor corrections, a reference
adde
Symmetry Breaking Boundary States and Defect Lines
We present a large and universal class of new boundary states which break
part of the chiral symmetry in the underlying bulk theory. Our formulas are
based on coset constructions and they can be regarded as a non-abelian
generalization of the ideas that were used by Maldacena, Moore and Seiberg to
build new boundary states for SU(N). We apply our expressions to construct
defect lines joining two conformal field theories with possibly different
central charge. Such defects can occur e.g. in the AdS/CFT correspondence when
branes extend to the boundary of the AdS-space.Comment: 36 pages, LaTeX, 1 figure, V1: typos corrected and references added,
v2: we added a short remark concerning the geometry of symmetry breaking
D-branes in group manifold
On the hierarchy of symmetry breaking D-branes in group manifolds
We construct the boundary WZNW functional for symmetry breaking D-branes on a
group manifold which are localized along a product of a number of twisted
conjugacy classes and which preserve an action of an arbitrary continuous
subgroup. These branes provide a geometric interpretation for the algebraic
formulation of constructing D-branes developed recently in hep-th/0203161. We
apply our results to obtain new symmetry breaking and non-factorizing D-branes
in the background SL(2,R) x SU(2).Comment: 34 page
Fermionic Coset, Critical Level W^(2)_4-Algebra and Higher Spins
The fermionic coset is a limit of the pure spinor formulation of the AdS5xS5
sigma model as well as a limit of a nonlinear topological A-model, introduced
by Berkovits. We study the latter, especially its symmetries, and map them to
higher spin algebras.
We show the following. The linear A-model possesses affine
\AKMSA{pgl}{4}{4}_0 symmetry at critical level and its \AKMSA{psl}{4}{4}_0
current-current perturbation is the nonlinear model. We find that the
perturbation preserves -algebra symmetry at critical
level. There is a topological algebra associated to \AKMSA{pgl}{4}{4}_0 with
the properties that the perturbation is BRST-exact. Further, the
BRST-cohomology contains world-sheet supersymmetric symplectic fermions and the
non-trivial generators of the -algebra. The Zhu functor
maps the linear model to a higher spin theory. We analyze its
\SLSA{psl}{4}{4} action and find finite dimensional short multiplets.Comment: 25 page