49 research outputs found
Open-closed string correspondence: D-brane decay in curved space
This paper analyzes the effect of curved closed string backgrounds on the
stability of D-branes within boundary string field theory. We identify the
non-local open string background that implements shifts in the closed string
background and analyze the tachyonic sector off-shell. The renormalization
group flow reveals some characteristic properties, which are expected for a
curved background, like the absence of a stable space-filling brane. In
3-dimensions we describe tachyon condensation processes to lower-dimensional
branes, including a curved 2-dimensional brane. We argue that this 2-brane is
perturbatively stable. This is in agreement with the known maximally symmetric
WZW-branes and provides further support to the bulk-boundary factorization
approach to open-closed string correspondence.Comment: 23 pages, harvma
On quantization of singular varieties and applications to D-branes
We calculate the ring of differential operators on some singular affine
varieties (intersecting stacks, a point on a singular curve or an orbifold).
Our results support the proposed connection of the ring of differential
operators with geometry of D-branes in (bosonic) string theory. In particular,
the answer does know about the resolution of singularities in accordance with
the string theory predictions.Comment: LaTeX2e, 17 pages, misprints correcte
Ising model with a boundary magnetic field - an example of a boundary flow
In hep-th/0312197 a nonperturbative proof of the g-theorem of Affleck and
Ludwig was put forward. In this paper we illustrate how the proof of
hep-th/0312197 works on the example of the 2D Ising model at criticality
perturbed by a boundary magnetic field. For this model we present explicit
computations of all the quantities entering the proof including various contact
terms. A free massless boson with a boundary mass term is considered as a
warm-up example.Comment: 1+20 pages, Latex, 2 eps figures; v2: references adde
Towards Integrability of Topological Strings I: Three-forms on Calabi-Yau manifolds
The precise relation between Kodaira-Spencer path integral and a particular
wave function in seven dimensional quadratic field theory is established. The
special properties of three-forms in 6d, as well as Hitchin's action
functional, play an important role. The latter defines a quantum field theory
similar to Polyakov's formulation of 2d gravity; the curious analogy with
world-sheet action of bosonic string is also pointed out.Comment: 31 page
Reformulation of Boundary String Field Theory in terms of Boundary State
We reformulate bosonic boundary string field theory in terms of boundary
state. In our formulation, we can formally perform the integration of target
space equations of motion for arbitrary field configurations without assuming
decoupling of matter and ghost. Thus, we obtain the general form of the action
of bosonic boundary string field theory. This formulation may help us to
understand possible interactions between boundary string field theory and the
closed string sector.Comment: 13 page
Unitary minimal models of SW(3/2,3/2,2) superconformal algebra and manifolds of G_2 holonomy
The SW(3/2,3/2,2) superconformal algebra is a W algebra with two free
parameters. It consists of 3 superconformal currents of spins 3/2, 3/2 and 2.
The algebra is proved to be the symmetry algebra of the coset
(su(2)+su(2)+su(2))/su(2). At the central charge c=21/2 the algebra coincides
with the superconformal algebra associated to manifolds of G_2 holonomy. The
unitary minimal models of the SW(3/2,3/2,2) algebra and their fusion structure
are found. The spectrum of unitary representations of the G_2 holonomy algebra
is obtained.Comment: 34 pages, 2 figures, latex; v2: added examples in appendix D; v3:
published version, corrected typo
Supersymmetric vertex algebras
We define and study the structure of SUSY Lie conformal and vertex algebras.
This leads to effective rules for computations with superfields.Comment: 71 page
Quantum Open-Closed Homotopy Algebra and String Field Theory
We reformulate the algebraic structure of Zwiebach's quantum open-closed
string field theory in terms of homotopy algebras. We call it the quantum
open-closed homotopy algebra (QOCHA) which is the generalization of the
open-closed homotopy algebra (OCHA) of Kajiura and Stasheff. The homotopy
formulation reveals new insights about deformations of open string field theory
by closed string backgrounds. In particular, deformations by Maurer Cartan
elements of the quantum closed homotopy algebra define consistent quantum open
string field theories.Comment: 36 pages, fixed typos and small clarifications adde
Non-commutative tachyon action and D-brane geometry
We analyse open string correlators in non-constant background fields,
including the metric , the antisymmetric -field, and the gauge field .
Working with a derivative expansion for the background fields, but exact in
their constant parts, we obtain a tachyonic on-shell condition for the inserted
functions and extract the kinetic term for the tachyon action. The 3-point
correlator yields a non-commutative tachyon potential. We also find a
remarkable feature of the differential structure on the D-brane: Although the
boundary metric plays an essential role in the action, the natural
connection on the D-brane is the same as in closed string theory, i.e. it is
compatible with the bulk metric and has torsion . This means, in
particular, that the parallel transport on the brane is independent of the
gauge field .Comment: 12 pages, no figure
Generalised discrete torsion and mirror symmetry for G_2 manifolds
A generalisation of discrete torsion is introduced in which different
discrete torsion phases are considered for the different fixed points or twist
fields of a twisted sector. The constraints that arise from modular invariance
are analysed carefully. As an application we show how all the different
resolutions of the T^7/Z_2^3 orbifold of Joyce have an interpretation in terms
of such generalised discrete torsion orbifolds. Furthermore, we show that these
manifolds are pairwise identified under G_2 mirror symmetry. From a conformal
field theory point of view, this mirror symmetry arises from an automorphism of
the extended chiral algebra of the G_2 compactification.Comment: LaTeX, 25 pages, 1 figure; v2: one reference added and comment about
higher loop modular invariance corrected, version to be publishe