Closure of the algebra of constraints for a nonprojectable Ho\v{r}ava model

We perform the Hamiltonian analysis for a nonprojectable Horava model whose potential is composed of R and R^2 terms. We show that Dirac's algorithm for the preservation of the constraints can be done in a closed way, hence the algebra of constraints for this model is consistent. The model has an extra, odd, scalar mode whose decoupling limit can be seen in a linear-order perturbative analysis on weakly varying backgrounds. Although our results for this model point in favor of the consistency of the Ho\v{r}ava theory, the validity of the full nonprojectable theory still remains unanswered.Comment: Some comments added in conclusions and abstract. Version published in Phys. Rev. D. 15 pages, 1 figur

Supersymmetry and cosmic censorship

We show that requiring unbroken supersymmetry everywhere in black-hole-type solutions of N=2,d=4 supergravity coupled to vector supermultiplets ensures in most cases absence of naked singularities. We show that the requirement of global supersymmetry implies the absence of sources for NUT charge, angular momentum, scalar hair and negative energy, for which there is no microscopic interpretation in String Theory. These conditions exclude, for instance, singular solutions such as the Kerr-Newman with M=|q|, which fails to be everywhere supersymmetric. There are, nevertheless, everywhere supersymmetric solutions with "global" angular momentum and non-trivial scalar fields. We also present similar preliminary results in N=1,d=5 supergravity coupled to vector multiplets.Comment: To be published in Talk given at the 2nd Workshop and Midterm Meeting of the Marie Curie RTN "Constituents, Fundamental Forces and Symmetries of the Universe", Naples, Italy, October 9-13 200

Caracterización de los procesos bio geoquímicos que controlan la especiación de hierro en el drenaje ácido de Mina Esperanza (España)

41 páginas.Trabajo Fin de Máster Oficial en Geología y Gestión Ambiental de los Recursos Minerales. Directores: Dr. Manuel Antonio Caraballo Monge ; Dr. José Miguel Nieto Liñán. El estudio de los procesos involucrados en la especiación de hierro de un drenaje ácido de Mina es esencial para conocer el impacto ambiental que genera, así como la aplicación que tiene sobre un tratamiento pasivo. El análisis se realizará en el agua ácida de un canal que conecta la bocamina de una galería inundada de Mina Esperanza con un sistema de tratamiento pasivo. Para ello se examinarán los parámetros fisicoquímicos así como la concentración de metales disueltos, haciendo especial hincapié en las especies de hierro disueltas. Mediante la realización de este estudio se pretende conocer más a fondo los procesos involucrados en la especiación de hierro en esta agua, tales como: oxidación biótica y abiótica de hierro ferroso o fotoreducción de hierro férrico. Del mismo modo se espera obtener un mejor conocimiento de la influencia que las variaciones estacionales pueden ejercer sobre los mencionados procesos. El estudio de los procesos involucrados en la especiación de hierro permitirá sumar observaciones que ayuden a mejorar tanto el funcionamiento de posibles sistemas de tratamiento pasivo como la comprensión que actualmente se tiene de estos ambientes acuáticos extremos

Supersymmetric solutions of N=2 d=4 sugra: the whole ungauged shebang

In this article we complete the classification of the supersymmetric solutions of N=2 D=4 ungauged supergravity coupled to an arbitrary number of vector- and hypermultiplets. We find that in the timelike case the hypermultiplets cause the constant-time hypersurfaces to be curved and have su(2) holonomy identical to that of the hyperscalar manifold. The solutions have the same structure as without hypermultiplets but now depend on functions which are harmonic in the curved 3-dimensional space. We discuss an example obtained from a hyper-less solution via the c-map. In the null case we find that the hyperscalars can only depend on the null coordinate and the solutions are essentially those of the hyper-less case.Comment: 27 pages, latex2

H-FGK formalism for black-hole solutions of N=2, d=4 and d=5 supergravity

We rewrite the Ferrara-Gibbons-Kallosh (FGK) black-hole effective action of N=2, d=4,5 supergravities coupled to vector multiplets, replacing the metric warp factor and the physical scalars with real variables that transform in the same way as the charges under duality transformations, which simplifies the equations of motion. For a given model, the form of the solution in these variables is the same for all spherically symmetric black holes, regardless of supersymmetry or extremality.Comment: 10 pages; v2: references added, some editing of the text, results unchanged; v3: references added as in the published versio

On the consistency of the Horava Theory

With the goal of giving evidence for the theoretical consistency of the Horava Theory, we perform a Hamiltonian analysis on a classical model suitable for analyzing its effective dynamics at large distances. The model is the lowest-order truncation of the Horava Theory with the detailed-balance condition. We consider the pure gravitational theory without matter sources. The model has the same potential term of general relativity, but the kinetic term is modified by the inclusion of an arbitrary coupling constant lambda. Since this constant breaks the general covariance under space-time diffeomorphisms, it is believed that arbitrary values of lambda deviate the model from general relativity. We show that this model is not a deviation at all, instead it is completely equivalent to general relativity in a particular partial gauge fixing for it. In doing this, we clarify the role of a second-class constraint of the model.Comment: The wording has been revised in general, specially in abstract, introduction and conclusions. No changes in results. Version published in IJMP