3,171 research outputs found
Quantum corrections to dynamical holographic thermalization: entanglement entropy and other non-local observables
We investigate the thermalization time scale in the planar limit of the SU(N)
N=4 SYM plasma at strong yet finite 't Hooft coupling by considering its
supergravity dual description, including the full O(alpha'^3) type IIB string
theory corrections. We also discuss on the effects of the leading non-planar
corrections. We use extended geometric probes in the bulk which are dual to
different non-local observables in the N=4 SYM theory. This is carried out
within the framework of dynamical holographic thermalization.Comment: 19 pages, 4 figures. V2: References added, 1 figure added, 1 figure
corrected, enlarged discussions about extended probes, typos corrected.
Published versio
Dynamics of holographic thermalization
Dynamical evolution of thin shells composed by different kinds of degrees of
freedom collapsing within asymptotically AdS spaces is explored with the aim of
investigating models of holographic thermalization of strongly coupled systems.
From the quantum field theory point of view this corresponds to considering
different thermal quenches. We carry out a general study of the thermalization
time scale using different parameters and space-time dimensions, by calculating
renormalized space-like geodesic lengths and rectangular minimal area surfaces
as extended probes of thermalization, which are dual to two-point functions and
rectangular Wilson loops. Different kinds of degrees of freedom in the shell
are described by their corresponding equations of state. We consider a scalar
field, as well as relativistic matter, a pressureless massive fluid and
conformal matter, which can be compared with the collapse of an AdS-Vaidya thin
shell. Remarkably, for conformal matter, the thermalization time scale becomes
much larger than the others. Furthermore, in each case we also investigate
models where the cosmological constants of the inner and outer regions
separated by the shell are different. We found that in this case only a scalar
field shell collapses, and that the thermalization time scale is also much
larger than the AdS-Vaidya case.Comment: 25 pages, 4 figures. V2: published versio
Strings and D-branes in curved space-time
In this thesis we study the AdS3 Wess-Zumino-Novikov-Witten model. We compute
the Operator Product Expansion of primary fields as well as their images under
the spectral flow automorphism in all sectors of the model by considering it as
a Wick rotation of the H3+ coset model. We argue that the symmetries of the
affine algebra require a truncation which establishes the closure of the fusion
rules on the Hilbert space of the theory. These results are then used to
discuss the factorization of four point functions by applying the bootstrap
approach.
We also study the modular properties of the model. Although the Euclidean
partition function is modular invariant, the characters on the Euclidean torus
diverge and the regularization proposed in the literature removes information
on the spectrum, so that the usual one to one map between characters and
representations of rational models is lost. Reconsidering the characters
defined on the Lorentzian torus and focusing on their structure as
distributions, we obtain expressions that recover those properties. We then
study their generalized modular properties and use them to discuss the relation
between modular data and one point functions associated to symmetric D-branes,
generalizing some results from Rational Conformal Field Theories in the
particular cases of point like and dS2 branes, such as Cardy type solutions or
Verlinde like formulas.Comment: 167 pages, PhD. Thesis, defended 15/03/2012, 9 figure
The generalized Bergshoeff-de Roo identification II
We recently introduced a T-duality covariant mechanism to compute all-order
higher-derivative interactions in the heterotic string. Here we extend the
formalism to account for a two-parameter family of corrections that also
include the bosonic string and HSZ theory. We use our result to compute the
full second order Double Field Theory (DFT) for generic values of the
parameters, including the generalized Green-Schwarz transformation and its
invariant action.Comment: 46 page
Uplifting non-compact gauged supergravities
We provide the M-theory uplift of de Sitter vacua of SO(5,3) and SO(4,4)
gaugings of maximal supergravity in 4 dimensions. We find new non-compact
backgrounds that are squashed hyperboloids with non-trivial flux for the 3-form
potential. The uplift requires a new non-linear ansatz for the 11-dimensional
metric and for the 3-form potential that reduces to the known one leading to
the 7-sphere solution in the case of the SO(8) gauging.Comment: 28 pages. v2: font fixed and clarified some points. JHEP versio
On supersymmetric D6‒D6 systems with magnetic fields
We study systems of D6 and D6 branes with non-zero world-volume magnetic fields in the weak coupling limit. We find two configurations for which the conditions for absence of tachyons in the spectra coincide exactly with those found in the low energy effective theory approach, for the systems to preserve 1/8 of the supersymmetries of the type IIA string theory vacuum. These conditions give rise to a four-parameter family of solutions in each case. We present further evidence of the stability of these systems by computing the lowest order interaction amplitude, verifying the no force condition as well as the supersymmetric character of the spectrum.Facultad de Ciencias ExactasInstituto de FÃsica La Plat
On supersymmetric D6‒D6 systems with magnetic fields
We study systems of D6 and D6 branes with non-zero world-volume magnetic fields in the weak coupling limit. We find two configurations for which the conditions for absence of tachyons in the spectra coincide exactly with those found in the low energy effective theory approach, for the systems to preserve 1/8 of the supersymmetries of the type IIA string theory vacuum. These conditions give rise to a four-parameter family of solutions in each case. We present further evidence of the stability of these systems by computing the lowest order interaction amplitude, verifying the no force condition as well as the supersymmetric character of the spectrum.Facultad de Ciencias ExactasInstituto de FÃsica La Plat
Quantum corrections to dynamical holographic thermalization: entanglement entropy and other non-local observables
We investigate the thermalization time scale in the planar limit of the SU(N) N=4 SYM plasma at strong yet finite ´t Hooft coupling by considering its supergravity dual description, including the full O(alpha´^3) type IIB string theory corrections. We also discuss on the effects of the leading non-planar corrections. We use extended geometric probes in the bulk which are dual to different non-local observables in the N=4 SYM theory. This is carried out within the framework of dynamical holographic thermalization.Instituto de FÃsica La PlataConsejo Nacional de Investigaciones CientÃficas y Técnica
The generalized Bergshoeff-de Roo identification
There are two main approaches to duality covariant first order higher derivative corrections to the heterotic string, one extending the duality structure and the other deforming the gauge transformations. In this paper we introduce a framework from which both approaches can be derived, proving their equivalence and extending them to higher orders.Instituto de FÃsica La Plat
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