Puntualizaciones sobre «La transición». Apropósito de un encuentro reciente

The object of this article is in fact a review of a spanish contribution to the topic on the ways from Antiquity to mediaeval times, in short, on the « transition». Ten studies are here presented, resumed and, if it is necessary, criticized with own references to its pages, where such affirmations are realized. There is also a up-date point of view on the late Antiquity and beyond

Para un nuevo debate sobre la crisis del s. III (en Hispania), al hilo de un estudio reciente

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¿Revolución en la antigüedad tardía? Un problema historiográfico

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Sobre las relaciones Iglesia-Estado en el Imperio

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Notas complementarias sobre el preámbulo del edicto del 301: ¿Lectura económica o histórica?

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A generalized non-Gaussian consistency relation for single field inflation

We show that a perturbed inflationary spacetime, driven by a canonical single scalar field, is invariant under a special class of coordinate transformations together with a field reparametrization of the curvature perturbation in co-moving gauge. This transformation may be used to derive the squeezed limit of the 3-point correlation function of the co-moving curvature perturbations valid in the case that these do not freeze after horizon crossing. This leads to a generalized version of Maldacena's non-Gaussian consistency relation in the sense that the bispectrum squeezed limit is completely determined by spacetime diffeomorphisms. Just as in the case of the standard consistency relation, this result may be understood as the consequence of how long-wavelength modes modulate those of shorter wavelengths. This relation allows one to derive the well known violation to the consistency relation encountered in ultra slow-roll, where curvature perturbations grow exponentially after horizon crossing.Comment: 16 pages, v3: matches published version (JCAP

Vanishing of local non-Gaussianity in canonical single field inflation

We study the production of observable primordial local non-Gaussianity in two opposite regimes of canonical single field inflation: attractor (standard single field slow-roll inflation) and non attractor (ultra slow-roll inflation). In the attractor regime, the standard derivation of the bispectrum's squeezed limit using co-moving coordinates gives the well known Maldacena's consistency relation $f_{NL} = 5(1-n_{s})/12$. On the other hand, in the non-attractor regime, the squeezed limit offers a substantial violation of this relation given by $f_{NL} = 5/2$. In this work we argue that, independently of whether inflation is attractor or non-attractor, the size of the observable primordial local non-Gaussianity is predicted to be $f_{NL}^{obs} = 0$ (a result that was already understood to hold in the case of attractor models). To show this, we follow the use of the so-called Conformal Fermi Coordinates (CFC), recently introduced in the literature. These coordinates parametrize the local environment of inertial observers in a perturbed FRW spacetime, allowing one to identify and compute gauge invariant quantities, such as $n$-point correlation functions. Concretely, we find that during inflation, after all the modes have exited the horizon, the squeezed limit of the 3-point correlation function of curvature perturbations vanishes in the CFC frame, regardless of the inflationary regime. We argue that such a cancellation should persist after inflation ends.Comment: 27 pages, v2:matches published version(JCAP

Accesibilidad web : un problema pendiente

El presente artículo plantea la necesidad de un cambio en el diseño accesible de los sitios web, teniendo en cuenta que no todos navegamos de igual manera ni tenemos las mismas habilidades o capacidades. También incide en la nueva legislación europea y española al respecto que obliga a instituciones y administraciones públicas a cumplir unos niveles mínimos de accesibilidad a partir de este mismo año 2006 y las consecuencias que estas leyes tienen en el sector de empresas relacionadas con el diseño y la producción de sitios web

Nuevas aportaciones al debate sobre las élites provinciales en la Hispania Romana

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Prosopographia theodosiana (I): entomo al llamado "clan hispano"

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