Type IIA Flux Vacua and α′\alpha'-corrections

We analyse type IIA Calabi-Yau orientifolds with backgroud fluxes, taking into account the effect of perturbative $\alpha'$-corrections. In particular, we consider the $\alpha'$-corrections that modify the metrics in the K\"ahler sector of the compactification. As it has been argued in the literature, including such $\alpha'$-corrections allows to construct the mirror duals of type IIB Calabi-Yau flux compactifications, in which the effect of flux backreaction is under control. We compute the $\alpha'$-corrected scalar potential generated by the presence of RR and NS fluxes, and reformulate it as a bilinear of the flux-axion polynomials invariant under the discrete shift symmetries of the compactification. The use of such invariants allows to express in a compact and simple manner the conditions for Minkowski and AdS flux vacua, and to extract the effect of $\alpha'$-corrections on them.Comment: 40 pages, typos corrected and references adde

Phase space analysis of quintessence fields trapped in a Randall-Sundrum Braneworld: anisotropic Bianchi I brane with a Positive Dark Radiation term

In this paper we investigate, from the dynamical systems perspective, the evolution of an scalar field with arbitrary potential trapped in a Randall-Sundrum's Braneworld of type 2. We consider an homogeneous but anisotropic Bianchi I (BI) brane filled also with a perfect fluid. We also consider the effect of the projection of the five-dimensional Weyl tensor onto the three-brane in the form of a positive Dark Radiation term. Using the center manifold theory we obtain sufficient conditions for the asymptotic stability of de Sitter solution with standard 4D behavior. We also prove that there are not late time de Sitter attractors with 5D-modifications since they are always saddle-like. This fact correlates with a transient primordial inflation. We present here sufficient conditions on the potential for the stability of the scalar field-matter scaling solution, the scalar field-dominated solution, and the scalar field-dark radiation scaling solution. We illustrate our analytical findings using a simple $f$-deviser as a toy model. All these results are generalizations of our previous results obtained for FRW branes.Comment: 14 pages, 11 figures, one affiliation added, matches the published version at CQG. arXiv admin note: substantial text overlap with arXiv:1110.173

Higgs inflation on the brane

We analyze the slow-roll inflation mechanism in brane framework with a real Higgs field confined on the brane. We prove that inflation occur for field value below the 4-dimensional Planck scale and produce cosmological perturbations in accordance with observations. Through the amplitude of the scalar perturbation produced during inflation we could determine the self-coupling constant of the Higgs field which is not predicted by the fundamental theories. Also it was found the solutions to the motion equations on the brane

Type IIA Flux Vacua and α′\alpha'-corrections

We analyse type IIA Calabi-Yau orientifolds with backgroud fluxes, taking into account the effect of perturbative $\alpha'$-corrections. In particular, we consider the $\alpha'$-corrections that modify the metrics in the K\"ahler sector of the compactification. As it has been argued in the literature, including such $\alpha'$-corrections allows to construct the mirror duals of type IIB Calabi-Yau flux compactifications, in which the effect of flux backreaction is under control. We compute the $\alpha'$-corrected scalar potential generated by the presence of RR and NS fluxes, and reformulate it as a bilinear of the flux-axion polynomials invariant under the discrete shift symmetries of the compactification. The use of such invariants allows to express in a compact and simple manner the conditions for Minkowski and AdS flux vacua, and to extract the effect of $\alpha'$-corrections on them.Comment: 40 page

Type IIA Flux Vacua with Mobile D6-branes

We analyse type IIA Calabi-Yau orientifolds with background fluxes and D6-branes. The presence of D6-brane deformation moduli redefines the 4d dilaton and complex structure fields and complicates the analysis of such vacua in terms of the effective Kahler potential and superpotential. One may however formulate the F-term scalar potential as a bilinear form on the flux-axion polynomials $\rho_A$ invariant under the discrete shift symmetries of the 4d effective theory. We express the conditions for Minkoswki and AdS flux vacua in terms of such polynomials, which allow to extend the analysis to include vacua with mobile D6-branes. We find a new, more general class of N = 0 Minkowski vacua, which nevertheless present a fairly simple structure of (contravariant) F-terms. We compute the soft-term spectrum for chiral models of intersecting D6-branes in such vacua, finding a quite universal pattern.Comment: 77 pages, 3 figures; v2: minor corrections and references adde

Type IIA flux vacua with mobile D6-branes and α '-corrections

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 15-03-2019Type IIA ux compacti cations have proven to be a rich framework to construct phenomenologically appealing string vacua. However, a better understanding of such a ux landscape in the presence of D-branes is required if one wants to nd realistic vacuum solutions. In this thesis, we study perturbative Type IIA ux vacua with an underlying Calabi-Yau geometry, by mean of the ux-axion polynomial formalism. In a rst stage we consider type IIA Calabi-Yau orientifolds with background uxes and rewrite the classical ux potential as a bilinear of ux-axion polynomials invariant under the discrete shift symmetries of the compacti cation. We perform a systematic search of purely closed string vacua, showing that one can easily rewrite the conditions for N = 0 Minkowski and N = 1 AdS in terms of simple algebraic equations on the axion polynomials. Then we turn to the search of vacua in compacti cations with uxes and mobile D6-branes. The presence of D6-brane moduli rede nes the four-dimensional dilaton and complex structure moduli and simultaneously destroy the nice factorization between K ahler and complex structure moduli in the K ahler potential, complicating the search of vacua in terms of the e ective K ahler potential and superpotential. Nevertheless, one may still express the F-term scalar potential as a bilinear of such polynomials, which allows us to nd a new and more general class of N = 0 Minkowski vacua, which present a quite simple structure of contravariant F-terms. We compute the set of soft supersymmetry breaking terms for chiral models of intersecting D6-branes in such vacua, nding a quite universal pattern. In a second stage we further study type IIA Calabi-Yau ux compacti cations with perturbative 0-corrections. It is a well-known fact that the inclusion of such 0-corrections allows to construct the mirror duals of type IIB Calabi-Yau ux compacti cations, in which the e ect of ux backreaction is under control. We compute the 0-corrected scalar potential generated by RR and NS uxes, and reformulate it as a bilinear of the ux-axion polynomials. The use of such invariants allows to express in a compact and simple way the conditions for N = 0 Minkowski and N = 1 AdS ux vacua, and to extract the e ect of 0-corrections on them.Las compacti caciones de la teor a de cuerda de tipo IIA con ujos de fondo han demostrado ser un marco rico para construir vac os de cuerdas fenomenol ogicamente atractivos. Sin embargo, si se quiere encontrar soluciones de vac o realistas, se requiere una mejor comprensi on de este paisaje de ujos en presencia de D-branas. En esta tesis, se estudian vac os perturbativos de tipo IIA con ujos y una geometr a Calabi-Yau subyacente, por medio del formalismo de los polinomios de axiones. En una primera etapa, se consideran Calabi-Yau orientifolds de tipo IIA en presencia de ujos y reescribimos el potencial cl asico generado por los ujos como un bilineal de los polinomios de axiones, los cuales son invariantes bajo las simetr as discretas de la compacti caci on. Utilizando este formalismo se realiza una b usqueda sistem atica de vac os de cuerdas cerradas, demostrando que uno puede reescribir f acilmente las condiciones de vac os de Minkowski nosupersim etricos y vac os AdS supersim etricos en t erminos de simples ecuaciones algebraicas en los polinomios de axiones. Luego comenzamos la b usqueda de vac os en compacti caciones que incluyen ujos y D6-branas m oviles. La presencia de los moduli de D6-branas rede ne los moduli de estructura compleja y el dilaton en cuatro dimensiones, y simult aneamente destruye la agradable factorizaci on entre los moduli de K ahler y los moduli de estructura compleja en el potencial de K ahler, lo que complica la b usqueda de vac os en t erminos del potencial de K ahler y el superpotencial. Sin embargo, el potencial escalar todav a puede ser expresado como un bilineal de los polinomios de axiones, lo que nos permite encontrar una clase nueva y m as general de vac os de Minkowski no-supersim etricos que presentan una estructura bastante simple de los F-terms contravariantes. Adem as, se calculan los t erminos de ruptura suave de supersimetr a para los campos quirales que viven en las intersecciones de las D6-branas en tales vac os, encontrando un patr on bastante universal. En una segunda etapa, se estudian compacti caciones de tipo IIA en Calabi- Yau que incluyen ujos y correcciones perturbativas de 0. Es un hecho bien conocido que la inclusi on de tales correcciones en el lado IIA, permite construir compacti caciones que son espejos duales de las compacti caciones de tipo IIB con ujos en las que la backreaction de los ujos est a bajo control. Se calcula el potencial escalar generado por los ujos y que incluye las correciones de 0, y lo reformulamos como un bilineal de los polinomios de axiones. El uso de tales invariantes permite expresar de manera compacta y sencilla las condiciones de vac os de Minkowski no-supersim etricos y vac os AdS supersim etricos y extraer los efectos de las correcciones de 0 en estos vac os