17,048 research outputs found
Conformal field theory construction for nonabelian hierarchy wave functions
The fractional quantum Hall effect is the paradigmatic example of
topologically ordered phases. One of its most fascinating aspects is the large
variety of different topological orders that may be realized, in particular
nonabelian ones. Here we analyze a class of nonabelian fractional quantum Hall
model states which are generalizations of the abelian Haldane-Halperin
hierarchy. We derive their topological properties and show that the
quasiparticles obey nonabelian fusion rules of type su(q)_k. For a subset of
these states we are able to derive the conformal field theory description that
makes the topological properties - in particular braiding - of the state
manifest. The model states we study provide explicit wave functions for a large
variety of interesting topological orders, which may be relevant for certain
fractional quantum Hall states observed in the first excited Landau level.Comment: extended introduction, added reference
D-brane effective action and tachyon condensation in topological minimal models
We study D-brane moduli spaces and tachyon condensation in B-type topological
minimal models and their massive deformations. We show that any B-type brane is
isomorphic with a direct sum of `minimal' branes, and that its moduli space is
stratified according to the type of such decompositions. Using the
Landau-Ginzburg formulation, we propose a closed formula for the effective
deformation potential, defined as the generating function of tree-level open
string amplitudes in the presence of D-branes. This provides a direct link to
the categorical description, and can be formulated in terms of holomorphic
matrix models. We also check that the critical locus of this potential
reproduces the D-branes' moduli space as expected from general considerations.
Using these tools, we perform a detailed analysis of a few examples, for which
we obtain a complete algebro-geometric description of moduli spaces and strata.Comment: 36 page
N=2 higher-derivative couplings from strings
We consider the Calabi-Yau reduction of the Type IIA eight derivative
one-loop stringy corrections focusing on the couplings of the four dimensional
gravity multiplet with vector multiplets and a tensor multiplet containing the
NS two-form. We obtain a variety of higher derivative invariants generalising
the one-loop topological string coupling, , controlled by the lowest order
Kahler potential and two new non-topological quantities built out of the
Calabi-Yau Riemann curvature.Comment: 43 page
Geometric Langlands Twists of N = 4 Gauge Theory from Derived Algebraic Geometry
We develop techniques for describing the derived moduli spaces of solutions
to the equations of motion in twists of supersymmetric gauge theories as
derived algebraic stacks. We introduce a holomorphic twist of N=4
supersymmetric gauge theory and compute the derived moduli space. We then
compute the moduli spaces for the Kapustin-Witten topological twists as its
further twists. The resulting spaces for the A- and B-twist are closely related
to the de Rham stack of the moduli space of algebraic bundles and the de Rham
moduli space of flat bundles, respectively. In particular, we find the
unexpected result that the moduli spaces following a topological twist need not
be entirely topological, but can continue to capture subtle algebraic
structures of interest for the geometric Langlands program.Comment: 55 pages; minor correction
Equivariant semi-topological K-homology and a theorem of Thomason
We generalize several comparison results between algebraic, semi-topological
and topological K-theories to the equivariant case with respect to a finite
group.Comment: Corrects error found by referee in Theorem 4.1. Final version, to
appear in J. of K-theor
On Classification of QCD defects via holography
We discuss classification of defects of various codimensions within a
holographic model of pure Yang-Mills theories or gauge theories with
fundamental matter. We focus on their role below and above the phase transition
point as well as their weights in the partition function. The general result is
that objects which are stable and heavy in one phase are becoming very light
(tensionless) in the other phase. We argue that the dependence of the
partition function drastically changes at the phase transition point, and
therefore it correlates with stability properties of configurations. Some
possible applications for study the QCD vacuum properties above and below phase
transition are also discussed.Comment: 21 pages, 2 figure
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