Einstein-Katz action, variational principle, Noether charges and the thermodynamics of AdS-black holes

In this paper we describe 4-dimensional gravity coupled to scalar and Maxwell fields by the Einstein-Katz action, that is, the covariant version of the "Gamma-Gamma $-$ Gamma-Gamma" part of the Hilbert action supplemented by the divergence of a generalized "Katz vector". We consider static solutions of Einstein's equations, parametrized by some integration constants, which describe an ensemble of asymptotically AdS black holes. Instead of the usual Dirichlet boundary conditions, which aim at singling out a specific solution within the ensemble, we impose that the variation of the action vanishes on shell for the broadest possible class of solutions. We will see that, when a long-range scalar "hair" is present, only sub-families of the solutions can obey that criterion. The Katz-Bicak-Lynden-Bell ("KBL") superpotential built on this (generalized) vector will then give straightforwardly the Noether charges associated with the spacetime symmetries (that is, in the static case, the mass). Computing the action on shell, we will see next that the solutions which obey the imposed variational principle, and with Noether charges given by the KBL superpotential, satisfy the Gibbs relation, the Katz vectors playing the role of "counterterms". Finally, we show on the specific example of dyonic black holes that the sub-class selected by our variational principle satisfies the first law of thermodynamics when their mass is defined by the KBL superpotential.Comment: Accepted for publication by JHE

Analysis of the status of the preferential school subsidy policy

La Ley de Subvención Escolar Preferencial surgió como respuesta a la crisis educativa de las reformas neoliberales iniciada en el año 1980 y que, ha devenido en que los sectores más pobres de la población alcancen niveles de conocimiento y habilidades suficientes para su desarrollo integral y crítico. El objetivo del artículo es reflexionar sobre la ley de subvención escolar preferencial como política educativa relacional y cuestionar la mirada de rendición de cuentas. Los procedimientos metodológicos utilizados en esta revisión se fundamentan en el paradigma socio-crítico para revisiones bibliográficas. Las reflexiones finales aluden a que los desafíos de las políticas educativas chilenas, a través de los colegios construyan comunidad educativa, erradicando de sus constructos el foco exclusivo en garantizar cobertura escolar, y ésta como rendición de cuentas; ocasionando que la política desagencie a los estudiantes a través de la estigmatización prioritarios o preferentes, eliminando la politización de los sujetos.The Law of Preferential School Subsidy arose in response to the educational crisis of the neoliberal reforms initiated in the 1980s, which has resulted in the poorest sectors of the population reaching levels of knowledge and skills insufficient for their integral and critical development. The objective of the article is to reflect on the law of preferential school subsidy as a relational educational policy and to question the view of accountability. Regarding methodological procedures, the socio-critical paradigm and bibliographic review were used. The final reflections allude to the challenges of Chilean educational policies through schools to build an educational community, eradicating from their constructs the exclusive focus on guaranteeing school coverage, and this as an accountability policy; causing the policy to ignore students ‘agency through the stigmatization as “priority” or “preferred”, eliminating the politicization of the subjects

New Charged Black Holes with Conformal Scalar Hair

A new class of four-dimensional, hairy, stationary solutions of the Einstein-Maxwell-Lambda system with a conformally coupled scalar field is constructed in this paper. The metric belongs to the Plebanski-Demianski family and hence its static limit has the form of the charged C-metric. It is shown that, in the static case, a new family of hairy black holes arises. They turn out to be cohomogeneity-two, with horizons that are neither Einstein nor homogenous manifolds. The conical singularities in the C-metric can be removed due to the back reaction of the scalar field providing a new kind of regular, radiative spacetime. The scalar field carries a continuous parameter proportional to the usual acceleration present in the C-metric. In the zero-acceleration limit, the static solution reduces to the dyonic Bocharova-Bronnikov-Melnikov-Bekenstein solution or the dyonic extension of the Martinez-Troncoso-Zanelli black holes, depending on the value of the cosmological constant.Comment: Published versio

Jurgen Habermas: democracy, inclusion of the other and constitutional patriotism from the ethics of the speech

El presente trabajo sobre la ética del discurso de Jurgen Habermas, da cuenta de las connotaciones y exigencias para una democracia con legitimidad política y moral en nuestra sociedad. Entendiendo que una democracia radical no es algo dado por una sola vez y para siempre, sino el resultado de un proceso comunicativo que permite articular intereses distintos, donde están en juego la identidad, la solidaridad, la inclusión del “otro” y el patriotismo constitucional, entre otras cosas. Es decir, se puede corregir y recuperar el ideario normativo de la democracia moderna reduciendo la hegemonía de la racionalidad instrumental.This paper about Jurgen Habermas, discourse ethics deals with the connotations and exigencies for a democracy with political legitimacy and moral content for our society. Understanding that a radical democracy isn’t found only once and forever, far from that, it is the result of a communicational progress that allows conjugation different interests, where identity, the solidarity, the inclusion of the other and the constitutional patriotism are present among other things, I mean, you can correct and recover the normative ideas of modern democracy by reducing the hegemony of the instrumental rationalization

Huellas epistémicas para una educación transformadora: Un primer acercamiento desde una sujeta social epistémica situada

La trayectoria epistémica que han desarrollado los latinoamericanos posee implicaciones en todos los ámbitos de la vida, por el cual la concientización refuerza el pensamiento decolonial, permitiendo apreciar la riqueza de la diversidad sociocultural. Asimismo, la educación es el pilar fundamental por el cual los sujetos sociales epistémicos situados educan y son educados en proceso de retroalimentación mutua, el cual es denominado como práctica educativa. El objetivo del artículo teórico es reflexionar sobre las huellas epistémicas para una educación transformadora y de calidad. Con respecto a los procedimientos metodológicos se utilizó el paradigma socio-crítico y revisión bibliográfica. Las reflexiones finales apuntan a que se debe ser conscientes de las huellas epistémicas que todos poseen; como sujetos latinoamericanos es un deber visibilizar y reflexionar que la educación posee sustentos y planteamientos ideológicos monoculturales y universales, visibilizando que cada persona es sujeto social situado cuando se logra evidenciar como un ser humano intersubjetivo en proceso constante de aprendizaje.The epistemic trajectory developed by Latin Americans has implications in all areas of life, where awareness reinforces decolonial thinking, allowing to appreciate the richness of socio-cultural diversity. Also, education is the fundamental pillar by which the epistemic social subjects are educated in the process of mutual feedback, called educational practice. The objective of the theoretical article is to reflect on epistemic traces for a transformative and better quality education; being the first approach of a situated epistemic social subject. According to the methodological procedures, the socio-critical paradigm and bibliographic review were used. The final reflections point out that there must be awareness of epistemic traces; Latin Americans must visualize and reflect that education possesses monocultural and universal ideological support and approaches, making visible that every person is a social situated subject when he or she becomes an intersubjective human being in the process of learning

Universal IR Holography, Scalar Fluctuations and Glueball spectra

We show that the d'Alembertian operator with a possible mass term in the AdS soliton and more general confining gravity dual backrounds admits infinitely many different spectra. These can be interpreted as different theories in the infrared and correspond to multitrace deformations of either the Dirichlet or the Neumann theory. We prove that all these fluctuations are normalizable and provide examples of their spectra. Therefore, the AdS soliton can be interpreted as giving a holographic RG flow between an universal UV theory at the AdS boundary and these infinitely many possibilities in the IR, obtained by deformations. The massive spectrum of the double trace deformation in $AdS_5$ allows the matching of the large-$N$ glueball masses of lattice $QCD_3$; the ratio of the ground states of the $2^{++}$ and $0^{++}$ channels are in full agreement with the lattice prediction. When considering $AdS_7$ and the 4-dimensional pure glue theory, a remarkably general picture emerges, where we can write formulas for the fluctuations that are in agreement with ones from holographic high-energy scattering and from AdS/CFT with IR and UV cut-off. We point out that this log branch in the IR in $D$-dimensions can be seen as the usual logarithmic branch of scalar fields saturating the Breitenlohner-Freedman bound in a conformally rescaled metric, with $AdS_{D-1}\times S^1$ asymptotics.Comment: 17 pages, 3 figures; reference adde

The Universe as a topological defect

Four-dimensional Einstein's General Relativity is shown to arise from a gauge theory for the conformal group, SO(4,2). The theory is constructed from a topological dimensional reduction of the six-dimensional Euler density integrated over a manifold with a four-dimensional topological defect. The resulting action is a four-dimensional theory defined by a gauged Wess-Zumino-Witten term. An ansatz is found which reduces the full set of field equations to those of Einstein's General Relativity. When the same ansatz is replaced in the action, the gauged WZW term reduces to the Einstein-Hilbert action. Furthermore, the unique coupling constant in the action can be shown to take integer values if the fields are allowed to be analytically continued to complex values.Comment: 18 pages, LaTex, 4 figures. Title of the published version changed to "Universe as a Topological defect" by the journa

Exact Hairy Black Holes and their Modification to the Universal Law of Gravitation

In this paper two things are done. First, it is pointed out the existence of exact asymptotically flat, spherically symmetric black holes when a self interacting, minimally coupled scalar field is the source of the energy momentum of the Einstein equations in four dimensions. The scalar field potential is the recently found to be compatible with the hairy generalization of the Plebanski-Demianski solution of general relativity. This paper describes the spherically symmetric solutions that smoothly connect the Schwarzschild black hole with its hairy counterpart. The geometry and scalar field are everywhere regular except at the usual Schwarzschild like singularity inside the black hole. The scalar field energy momentum tensor satisfies the null energy condition in the static region of the spacetime. The first law holds when the parameters of the scalar field potential are fixed under thermodynamical variation. Secondly, it is shown that an extra, dimensionless parameter, present in the hairy solution, allows to modify the gravitational field of a spherically symmetric black hole in a remarkable way. When the dimensionless parameter is increased, the scalar field generates a flat gravitational potential, that however asymptotically matches the Schwarzschild gravitational field. Finally, it is shown that a positive cosmological constant can render the scalar field potential convex if the parameters are within a specific rank.Comment: Two new references, 10 pages, 2 figure

Remarks on the Myers-Perry and Einstein Gauss-Bonnet Rotating Solutions

The Kerr-type solutions of the five-dimensional Einstein and Einstein-Gauss-Bonnet equations look pretty similar when written in Kerr-Schild form. However the Myers-Perry spacetime is circular whereas the rotating solution of the Einstein-Gauss-Bonnet theory is not. We explore some consequences of this difference in particular regarding the (non) existence of Boyer-Lindquist-type coordinates and the extension of the manifold