117 research outputs found
Self-Duality and New TQFTs for Forms
We discuss theories containing higher-order forms in various dimensions. We
explain how Chern--Simons-type theories of forms can be defined from TQFTs in
one less dimension. We also exhibit new TQFTs with interacting Yang--Mills
fields and higher--order forms. They are obtained by the dimensional reduction
of TQFTs whose gauge functions are free self-duality equations. Interactions
are due to the gauging of global internal symmetries after dimensional
reduction. We list possible symmetries and give a brief discussion on the
possible relation of such systems to interacting field theories.Comment: teX-fil
On Least Action D-Branes
We discuss the effect of relevant boundary terms on the nature of branes.
This is done for toroidal and orbifold compactifications of the bosonic string.
Using the relative minimalization of the boundary entropy as a guiding
principle, we uncover the more stable boundary conditions at different regions
of moduli space. In some cases, Neumann boundary conditions dominate for small
radii while Dirichlet boundary conditions dominate for large radii. The c=1 and
c=2 moduli spaces are studied in some detail. The antisymmetric background
field B is found to have a more limited role in the case of Dirichlet boundary
conditions. This is due to some topological considerations. The results are
subjected to T-duality tests and the special role of the points in moduli space
fixed under T-duality is explained from least-action considerations.Comment: Latex, 20 pages, 2 figures, references adde
Geometry And Quantum Noise
We study the fine structure of long-time quantum noise in correlation
functions of AdS/CFT systems. Under standard assumptions of quantum chaos for
the dynamics and the observables, we estimate the size of exponentially small
oscillations and trace them back to geometrical features of the bulk system.
The noise level is highly suppressed by the amount of dynamical chaos and the
amount of quantum impurity in the states. This implies that, despite their
missing on the details of Poincare recurrences, `virtual' thermal AdS phases do
control the overall noise amplitude even at high temperatures where the thermal
ensemble is dominated by large AdS black holes. We also study EPR correlations
and find that, in contrast to the behavior of large correlation peaks, their
noise level is the same in TFD states and in more general highly entangled
states.Comment: 30 pages. 4 figure
Conformal Complementarity Maps
We study quantum cosmological models for certain classes of bang/crunch
singularities, using the duality between expanding bubbles in AdS with a FRW
interior cosmology and perturbed CFTs on de Sitter space-time. It is pointed
out that horizon complementarity in the AdS bulk geometries is realized as a
conformal transformation in the dual deformed CFT. The quantum version of this
map is described in full detail in a toy model involving conformal quantum
mechanics. In this system the complementarity map acts as an exact duality
between eternal and apocalyptic Hamiltonian evolutions. We calculate the
commutation relation between the Hamiltonians corresponding to the different
frames. It vanishes only on scale invariant states.Comment: 38 pages, 9 figure
On Some Universal Features of the Holographic Quantum Complexity of Bulk Singularities
We perform a comparative study of the time dependence of the holographic
quantum complexity of some space like singular bulk gravitational backgrounds.
This is done by considering the two available notions of complexity, one that
relates it to the maximal spatial volume and the other that relates it to the
classical action of the Wheeler-de Witt patch. We calculate and compare the
leading and the next to leading terms and find some universal features. The
complexity decreases towards the singularity for both definitions, for all
types of singularities studied. In addition the leading terms have the same
quantitative behavior for both definitions in restricted number of cases and
the behaviour itself is different for different singular backgrounds. The
quantitative details of the next to leading terms, such as their specific form
of time dependence, are found not to be universal. They vary between the
different cases and between the different bulk definitions of complexity. We
also address some technical points inherent to the calculation.Comment: 24 pages, 6 figures. v2: minor correction
Defects, Super-Poincar\'{e} line bundle and Fermionic T-duality
Topological defects are interfaces joining two conformal field theories, for
which the energy momentum tensor is continuous across the interface. A class of
the topological defects is provided by the interfaces separating two bulk
systems each described by its own Lagrangian, where the two descriptions are
related by a discrete symmetry.
In this paper we elaborate on the cases in which the discrete symmetry is a
bosonic or a fermionic T- duality. We review how the equations of motion
imposed by the defect encode the general bosonic T- duality transformations for
toroidal compactifications. We generalize this analysis in some detail to the
case of topological defects allowed in coset CFTs, in particular to those
cosets where the gauged group is either an axial or vector U(1). This is
discussed in both the operator and Lagrangian approaches. We proceed to
construct a defect encoding a fermionic T-duality. We show that the fermionic
T-duality is implemented by the Super-Poincar\'{e} line bundle. The observation
that the exponent of the gauge invariant flux on a defect is a kernel of the
Fourier-Mukai transform of the Ramond-Ramond fields, is generalized to a
fermionic T-duality. This is done via a fiberwise integration on
supermanifolds.Comment: 41 page
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