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 Kähler potential and superpotential. One may however formulate the F-term scalar potential as a bilinear form on the flux-axion polynomials ρ 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. arXiv:1811.09282v2 [hep-th]

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 II. We consider an homogeneous and isotropic Friedmann-Robertson-Walker (FRW) brane filled also with a perfect fluid. Center Manifold Theory is employed to obtain sufficient conditions for the asymptotic stability of de Sitter solution. We obtain conditions on the potential for the stability of scaling solutions as well for the stability of the scalar-field dominated solution. We prove the there are not late time attractors with 5D-modifications (they are saddle-like). This fact correlates with a transient primordial inflation. In the particular case of a scalar field with potential V = V0e−χφ + Λ we prove that for χ < 0 the de Sitter solution is asymptotically stable. However, for χ > 0 the de Sitter solution is unstable (of saddle type).

We analyse type IIA Calabi-Yau orientifolds with background fluxes, taking into account the effect of perturbative α -corrections. In particular, we consider the αcorrections that modify the metrics in the Kähler sector of the compactification. As it has been argued in the literature, including such α -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 α -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 α -corrections on them.arXiv:1812.08735v2 [hep-th]