Aspects of type IIA AdS4 orientifold vacua

Specialist level

Speaker:

Joan Quirant Pellín

Location&Place:

IFT Seminar Room/Red Room

Abstract:

In this thesis we explore the vacua structure of type IIA orientifold (CY) compactifications with fluxes, both from the 4d and the 10d point of view.

We start by reviewing type IIA Calabi-Yau orientifold compactifications with fluxes. First we consider only RR and NSNS fluxes, and then add (non)-geometric fluxes. We recall how the potential created by the fluxes can be rewritten as a bilinear expression and review the main swampland conjectures involving these scenarios.

Once the basics have been setted, we perform a systematic search of vacua, using directly the 4d effective action and the potential generated. We focus first on the case with only RR and NSNS fluxes and then repeat the same game by including geometric fluxes. We find several families of SUSY and non-SUSY AdS4 vacua.

We check which of them are stable and which have separation of scales.

We then put on the 10d glasses to analyse from the 10d perspective the SUSY vacua derived in the 4d effective theory. We comment on how an uplift to SU(3) structure manifolds does not exist unless the O6 planes are smeared. We then go beyond this approximation and look for an uplift in SU(3)×SU(3) structure manifolds, considering only the case with RR and NSNS fluxes. To do so, we expand the equations of motion in terms of gs. At zeroth order we recover the smeared approximation. We solve the expansion at first order, where the localised nature of the O6-planes is taken into account.

After this, we use the same machinery to study the non-perturbative stability of some of the families of non-SUSY vacua with only RR and NSNS fluxes. According to a refined version of the weak gravity conjecture, there should be membranes in the spectrum with Q > T, triggering its decay. We see that D8 branes wrapping the internal manifold with D6 branes ending on them can satisfy this requirement, making these vacua unstable.

We finish the thesis by recapping all the results and making some comments about which questions are still open, as well as possible future lines of research.