A new class of de Sitter vacua in String Theory Compactifications

Abstract: We revisit the stability of the complex structure moduli in the large volume regime of type-IIB flux compactifications. We argue that when the volume is not exponentially large, such as in K\"ahler uplifted dS vacua, the quantum corrections to the tree-level mass spectrum can induce tachyonic instabilities in this sector. We discuss a Random Matrix Theory model for the classical spectrum of the complex structure fields, and derive a new stability bound involving the compactification volume and the (very large) number of moduli. We also present a new class of vacua for this sector where the mass spectrum presents a finite gap, without invoking large supersymmetric masses. At these vacua the complex structure sector is protected from tachyonic instabilities even at non-exponential volumes. A distinguishing feature is that all fermions in this sector are lighter than the gravitino.