Iconografía del rostro frontal en la cerámica ibérica

Sin resume

Dynamical variables in gauge-translational gravity

Assuming that the natural gauge group of gravity is given by the group of isometries of a given space, for a maximally symmetric space we derive a model in which gravity is essentially a gauge theory of translations. Starting from first principles we verify that a nonlinear realization of the symmetry provides the general structure of this gauge theory, leading to a simple choice of dynamical variables of the gravity field corresponding, at first-order, to a diagonal matrix, whereas the non-diagonal elements contribute only to higher orders. © 2011 World Scientific Publishing Company.We acknowledge Prof. A. Fern´andez-Ra˜nada and J. Mart´ın-Mart´ın for useful discussions.Peer Reviewe

Nonlinear gauge realization of spacetime symmetries including translations

We present a general scheme for the nonlinear gauge realizations of space-time groups on coset spaces of the groups considered. In order to show the relevance of the method for the rigorous treatment of the translations in gravitational gauge theories, we apply it in particular to the affine group. This is an illustration of the family of spacetime symmetries having the form of a semidirect product H ⊗ T, where H is the stability subgroup and T are the translations. The translational component of the connection behaves like a true tensor under H when coset realizations are involved. c Plenum Publishing CorporationPeer Reviewe

The Husain-Kuchar Model: Time Variables and Non-degenerate Metrics

We study the Husain-Kuchar model by introducing a new action principle similar to the self-dual action used in the Ashtekar variables approach to Quantum Gravity. This new action has several interesting features; among them, the presence of a scalar time variable that allows the definition of geometric observables without adding new degrees of freedom, the appearance of a natural non-degenerate four-metric and the possibility of coupling ordinary matter.Comment: LaTeX, 22 pages, accepted for publication in Phys. Rev.

A perturbation approach to translational gravity

Within a gauge formulation of 3+1 gravity relying on a nonlinear realization of the group of isometries of space-time, a natural expansion of the metric tensor arises and a simple choice of the gravity dynamical variables is possible. We show that the expansion parameter can be identified with the gravitational constant and that the first-order depends only on a diagonal matrix in the ensuing perturbation approach. The explicit first-order solution is calculated in the static isotropic case, and its general structure is worked out in the harmonic gauge. © World Scientific Publishing Company.Work partially supported (J. Julve) by the Project MICINN FIS2009-11893.Peer Reviewe

Las cerámicas tartésicas con decoración geométrica: ¿ornamento o narración? algunas observaciones

Desde los tiempos neolíticos se han registrado por toda Europa, ciertas representaciones de signos geométricos que alcanzan inmutables hasta la edad del hierro. Parece indudable, en origen, su contenido simbólico pero llegados a fechas más tempranas es discutible esta afirmación. Tomando como referencia las cerámicas geométricas tartésicas y siguiendo pautas estrictamente iconográficas nos proponemos ahondar en este tema y, en última instancia responder a esta pregunta ¿poseen significado real estos signos o ya sólo se conservan como puro ornamento? Veremos que hay argumentos para defender ambos criterios