Challenges for D-brane large-field inflation with stabilizer fields

We study possible string theory compactifications which, in the low-energy limit, describe chaotic inflation with a stabilizer field. We first analyze type IIA setups where the inflationary potential arises from a D6-brane wrapping an internal three-cycle, and where the stabilizer field is either an open-string or bulk K\"ahler modulus. We find that after integrating out the relevant closed-string moduli consistently, tachyonic directions arise during inflation which cannot be lifted. This is ultimately due to the shift symmetries of the type IIA K\"ahler potential at large compactification volume. This motivates us to search for stabilizer candidates in the complex structure sector of type IIB orientifolds, since these fields couple to D7-brane Wilson lines and their shift symmetries are generically broken away from the large complex structure limit. However, we find that in these setups the challenge is to obtain the necessary hierarchy between the inflationary and Kaluza-Klein scales.Comment: 26 pages, typos corrected and comments added. Published versio

Extension of the adiabatic regularization method to spin-1/2 fields

The adiabatic regularization method was designed by L. Parker [1] for scalar fields in order to to subtract the potentially UV divergences that appear in the particle number operator. After that the method was generalized [2] to remove, in a consistent way, the UV divergences that appear in the expectation value of the stress-energy tensor 〈Tμv〉 in homogeneous cosmological backgrounds. We are going to provide here the extension of the adiabatic regularization method to spin-1/2 fields first given in [3]. In order to achieve this extension we will show the generalization of the adiabatic expansion for fermionic fields which differs significantly from the WKB-type expansion that works for the scalar modes. We will also show the consistency of the extended method computing well-known results, computed by other renormalization methods for a Dirac field in a FLRW spacetime, like the conformal and axial anomalies. Finally we will compute the expectation value of the stress-energy tensor for a Dirac field in a de Sitter spacetimeSEVERO OCHOA Progra

Flux Flattening in Axion Monodromy Inflation

String theory models of axion monodromy inflation exhibit scalar potentials which are quadratic for small values of the inflaton field and evolve to a more complicated function for large field values. Oftentimes the large field behaviour is gentler than quadratic, lowering the tensor-to-scalar ratio. This effect, known as flattening, has been observed in the string theory context through the properties of the DBI+CS D-brane action. We revisit such flattening effects in type IIB flux compactifications with mobile D7-branes, with the inflaton identified with the D7-brane position. We observe that, with a generic choice of background fluxes, flattening effects are larger than previously observed, allowing to fit these models within current experimental bounds. In particular, we compute the cosmological observables in scenarios compatible with closed-string moduli stabilisation, finding tensor-to-scalar ratios as low as r ~ 0.04. These are models of single field inflation in which the inflaton is much lighter than the other scalars through a mild tuning of the compactification data.Comment: 56 pages, 11 plot

Robust DEA efficiency scores: A probabilistic/combinatorial approach

In this paper we propose robust efficiency scores for the scenario in which the specification of the inputs/outputs to be included in the DEA model is modelled with a probability distribution. This proba- bilistic approach allows us to obtain three different robust efficiency scores: the Conditional Expected Score, the Unconditional Expected Score and the Expected score under the assumption of Maximum Entropy principle. The calculation of the three efficiency scores involves the resolution of an exponential number of linear problems. The algorithm presented in this paper allows to solve over 200 millions of linear problems in an affordable time when considering up 20 inputs/outputs and 200 DMUs. The approach proposed is illustrated with an application to the assessment of professional tennis players

La libertad religiosa en el Derecho Comunitario

El ISSN corresponde a la versión electrónica del documentoAunque, como es sabido, los Tratados constitutivos de la Unión Europea carecen de una Bill of Rights, de un catálogo oficial de derechos reconocidos, no les son ajenas las medidas de protección de los derechos y libertades fundamentales, máxime teniendo en cuenta la actividad en que en este punto ha desarrollado el Tribunal de Justicia de las Comunidades Europeas. Probar esta afirmación será el objetivo fundamental de este trabajo

La libertad religiosa en el Derecho español. Gestión de Antonio Garrigues en la revisión del Concordato de 1953 (1967-1970). [Reseña]

Reseña de: María Blanco, La libertad religiosa en el Derecho español. Gestión de Antonio Garrigues en la revisión del Concordato de 1953 (1967-1970), Editorial Thomson Aranzadi (The Global Law Collection), Cizur Menor 2006, 324 pp

Introducción a la Historia de las fuentes del Derecho canónico. El Derecho Antiguo hasta el Decretum de Graciano. [Reseña]

Reseña de: Brian Edwin Ferme, Introducción a la Historia de las fuentes del Derecho canónico. El Derecho Antiguo hasta el Decretum de Graciano, Editorial de la Universidad Católica Argentina, traducido por Nelson Carlos Dellaferrera, Buenos Aires 2006, 236 pp