Membrane-mediated vacuum decays, three-forms and the Weak Gravity Conjecture

In the context of four-dimensional effective theories deriving from string compactifications, the scalar potential depends on the fluxes of some p-forms in the extra dimensions. It is knownáthat membranes can mediate decays among different vacua of the potential, causing a change in the values of the fluxes. The aim of the thesis is to study this kind of transitions among AdS vacua in a specific model of flux compactification,áemploying a recent formulation of the effective four-dimensional theory that involves gauge three-forms. This novel perspective also allows for an investigation of the role of membranes in relation to the Weak Gravity Conjecture, giving some more general insight into the possibility of decay.