72 research outputs found
Branes at Orbifolds versus Hanany Witten in Six Dimensions
We reconstruct non-trivial 6d theories obtained by Blum and Intriligator by
considering IIB or SO(32) 5 branes at ALE spaces in the language of Hanany
Witten setups. Using ST duality we make the equivalence of the two approaches
manifest, thereby uncovering several new T-duality relations between the group
theoretic data describing the embedding of the instantonic 5 brane in the ALE
and brane positions in the Hanany Witten language. We construct several new 6d
theories, which can be understood as arising on 5 branes in IIB orientifolds
with oppositely charged orientifold planes recently introduced by Witten.Comment: 24 pages, LaTeX2e, 11 figures, using utarticle.cls (included). Typos
corrected, Acknowledgements adde
Matrix Description of M-theory on
We give some evidence that the worldvolume theory of the M-theory KK 6-brane
is governed by a non-critical membrane theory. We use this theory to give a
matrix description of M-theory on .Comment: 12 pages, LaTeX2e, using utarticle.cls (included
On Superpotentials for D-Branes in Gepner Models
A large class of D-branes in Calabi-Yau spaces can be constructed at the
Gepner points using the techniques of boundary conformal field theory. In this
note we develop methods that allow to compute open string amplitudes for such
D-branes. In particular, we present explicit formulas for the products of open
string vertex operators of untwisted A-type branes. As an application we show
that the boundary theories of the quintic associated with the special
Lagrangian submanifolds Im \omega_i z_i = 0 where \omega_i^5=1 possess no
continuous moduli.Comment: 33 pages, 2 figure
Entanglement entropy through conformal interfaces in the 2D Ising model
We consider the entanglement entropy for the 2D Ising model at the conformal
fixed point in the presence of interfaces. More precisely, we investigate the
situation where the two subsystems are separated by a defect line that
preserves conformal invariance. Using the replica trick, we compute the
entanglement entropy between the two subsystems. We observe that the entropy,
just like in the case without defects, shows a logarithmic scaling behavior
with respect to the size of the system. Here, the prefactor of the logarithm
depends on the strength of the defect encoded in the transmission coefficient.
We also comment on the supersymmetric case.Comment: 27 pages, 3 figures, v2: additional references and minor correction
A quick guide to defect orbifolds
We provide a lightning review of the construction of (generalised) orbifolds
[arXiv:0909.5013, arXiv:1210.6363] of two-dimensional quantum field theories in
terms of topological defects, along the lines of [arXiv:1307.3141]. This
universal perspective has many applications, some of which we sketch in the
examples of 2d Yang-Mills theory, Landau-Ginzburg models, and rational CFT.Comment: 11 pages, contribution to the String-Math 2013 proceeding
Fusion of Critical Defect Lines in the 2D Ising Model
Two defect lines separated by a distance delta look from much larger
distances like a single defect. In the critical theory, when all scales are
large compared to the cutoff scale, this fusion of defect lines is universal.
We calculate the universal fusion rule in the critical 2D Ising model and show
that it is given by the Verlinde algebra of primary fields, combined with group
multiplication in O(1,1)/Z_2. Fusion is in general singular and requires the
subtraction of a divergent Casimir energy.Comment: 17 page
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