167 research outputs found
Thermal Correlators in Little String Theory
We calculate, using holographic duality, the thermal two-point function in
finite temperature little string theory. The analysis of those correlators
reveals possible instabilities of the thermal ensemble, as in previous
discussions of the thermodynamics of little string theory. We comment on the
dependence of the instability on the spatial volume of the system.Comment: 13 page
Aspects of higher curvature terms and U-duality
We discuss various aspects of dimensional reduction of gravity with the
Einstein-Hilbert action supplemented by a lowest order deformation formed as
the Riemann tensor raised to powers two, three or four. In the case of R^2 we
give an explicit expression, and discuss the possibility of extended coset
symmetries, especially SL(n+1,Z) for reduction on an n-torus to three
dimensions. Then we start an investigation of the dimensional reduction of R^3
and R^4 by calculating some terms relevant for the coset formulation, aiming in
particular towards E_8(8)/(Spin(16)/Z_2) in three dimensions and an
investigation of the derivative structure. We emphasise some issues concerning
the need for the introduction of non-scalar automorphic forms in order to
realise certain expected enhanced symmetries.Comment: 26 pp., 15 figs., plain te
Proposals for Innovation and Improvement of the Quality of Life in Caprine Pastoralist Communities of Subsistence in the Monte Desert, Argentina
In a satisfactory alliance between the main environmental policy organizations and the academy, the National Observatory on Land Degradation and Desertification (ONDTyT) is created. The ONDTyD provides information regarding status and trends of land degradation/desertification in order to promote prevention and mitigation measures used for advising public and private decision-makers in Argentina. It is based in the development of 17 Pilot Sites that constitutes the local level network, providing bio-physical and socio-economic indicators of land degradation.
In this network the pilot site of the Monte, the largest dry region of Argentina (Lavalle desert, Mendoza), aims to improve the living conditions of native communities dedicated to subsistence goat farming, located below the poverty line. Precipitation ranges from 80-100 mm/year, strongly affecting productive activities. The proposal includes innovative traits in an area whose natural resources have been devastated. It is framed within a conception of rural territory development generating sustainable development strategies of rural indigenous communities, improve the status of the ecosystem through an integral management of natural and cultural resources, and improve socioeconomic conditions of inhabitants, compatibilizing ecosystem regeneration with investment in infrastructure and services, diversification of productive activities and generation of employment.
An interdisciplinary group designed the proposal and the integrated desertification assessment in the fields with active community participation through their knowledge, land and livestock. The pilot case can be replicated throughout the territory. The work combines participatory and integrated methodologies, showing that the Observatory is a successful example of partnership building between the political and scientific-technological sectors in Argentina
Real time response on dS_3: the Topological AdS Black Hole and the Bubble
We study real time correlators in strongly coupled N=4 supersymmetric
Yang-Mills theory on dS_3 x S^1, with antiperiodic boundary conditions for
fermions on the circle. When the circle radius is larger than a critical value,
the dual geometry is the so-called "topological AdS_5 black hole". Applying the
Son- Starinets recipe in this background we compute retarded glueball
propagators which exhibit an infinite set of poles yielding the quasinormal
frequencies of the topological black hole. The imaginary parts of the
propagators exhibit thermal effects associated with the Gibbons-Hawking
temperature due to the cosmological horizon of the de Sitter boundary. We also
obtain R-current correlators and find that after accounting for a small
subtlety, the Son-Starinets prescription yields the retarded Green's functions.
The correlators do not display diffusive behaviour at late times. Below the
critical value of the circle radius, the topological black hole decays to the
AdS_5 "bubble of nothing". Using a high frequency WKB approximation, we show
that glueball correlators in this phase exhibit poles on the real axis. The
tunnelling from the black hole to the bubble is interpreted as a hadronization
transition.Comment: 52 pages, 11 figures, typos corrected, references adde
Hydrodynamics from charged black branes
We extend the recent work on fluid-gravity correspondence to charged
black-branes by determining the metric duals to arbitrary charged fluid
configuration up to second order in the boundary derivative expansion. We also
derive the energy-momentum tensor and the charge current for these
configurations up to second order in the boundary derivative expansion. We find
a new term in the charge current when there is a bulk Chern-Simons interaction
thus resolving an earlier discrepancy between thermodynamics of charged
rotating black holes and boundary hydrodynamics. We have also confirmed that
all our expressions are covariant under boundary Weyl-transformations as
expected.Comment: 0+ 31 Pages; v2: 0+33 pages, typos corrected and new sections (in
appendix) added; v3:published versio
Scalar and vector mesons of flavor chiral symmetry breaking in the Klebanov-Strassler background
Recently, Dymarsky, Kuperstein and Sonnenschein constructed an embedding of
flavor D7- and anti-D7-branes in the Klebanov-Strassler geometry that breaks
the supersymmetry of the background, yet is stable. In this article, we study
in detail the spectrum of vector mesons in this new model of flavor chiral
symmetry breaking and commence an analytical analysis of the scalar mesons in
this setup.Comment: v1: 35 pages, 5 figures, 4 tables, includes self-contained review of
DKS construction; v2: corrected signs in eqs. (2.22) and (2.23), improved
discussion of scalar mesons in section 3.2; v3: major revision of the results
on scalar mesons, version submitted to JHEP; v4: version accepted by JHE
Deconstructing holographic liquids
We argue that there exist simple effective field theories describing the
long-distance dynamics of holographic liquids. The degrees of freedom
responsible for the transport of charge and energy-momentum are Goldstone
modes. These modes are coupled to a strongly coupled infrared sector through
emergent gauge and gravitational fields. The IR degrees of freedom are
described holographically by the near-horizon part of the metric, while the
Goldstone bosons are described by a field-theoretical Lagrangian. In the cases
where the holographic dual involves a black hole, this picture allows for a
direct connection between the holographic prescription where currents live on
the boundary, and the membrane paradigm where currents live on the horizon. The
zero-temperature sound mode in the D3-D7 system is also re-analyzed and
re-interpreted within this formalism.Comment: 21 pages, 2 figure
Charged, conformal non-relativistic hydrodynamics
We embed a holographic model of an U(1) charged fluid with Galilean
invariance in string theory and calculate its specific heat capacity and
Prandtl number. Such theories are generated by a R-symmetry twist along a null
direction of a N=1 superconformal theory. We study the hydrodynamic properties
of such systems employing ideas from the fluid-gravity correspondence.Comment: 31 pages, 1 figure, JHEP3 style, refs added, typos corrected, missing
terms in spatial charge current and field corrections added, to be published
in JHE
Non-conformal Hydrodynamics in Einstein-dilaton Theory
In the Einestein-dilaton theory with a Liouville potential parameterized by
, we find a Schwarzschild-type black hole solution. This black hole
solution, whose asymptotic geometry is described by the warped metric, is
thermodynamically stable only for . Applying the gauge/gravity
duality, we find that the dual gauge theory represents a non-conformal thermal
system with the equation of state depending on . After turning on the
bulk vector fluctuations with and without a dilaton coupling, we calculate the
charge diffusion constant, which indicates that the life time of the quasi
normal mode decreases with . Interestingly, the vector fluctuation with
the dilaton coupling shows that the DC conductivity increases with temperature,
a feature commonly found in electrolytes.Comment: 27 pages and 2 figures, published in JHE
Lectures on hydrodynamic fluctuations in relativistic theories
These are pedagogical lecture notes on hydrodynamic fluctuations in normal
relativistic fluids. The lectures discuss correlation functions of conserved
densities in thermal equilibrium, interactions of the hydrodynamic modes, an
effective action for viscous fluids, and the breakdown of the derivative
expansion in hydrodynamics.Comment: 55 pages. Based on lectures given at the Seattle INT Summer School on
Applications of String Theory in July 201
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