Uplifts in the penumbra: features of the moduli potential away from infinite-distance boundaries

Abstract The construction of meta-stable four-dimensional de Sitter vacua in type IIB string compactifications represents an important question and an ongoing area of work. There is considerable support both for stringy de Sitter vacua in the interior of moduli space and for their scarceness in the strict asymptotic regime towards infinite-distance boundaries of the compactification moduli space. Here, we present evidence for the existence of uplifting vacua in the three-form flux-induced scalar potential of the complex structure moduli of type IIB string theory on Calabi-Yau orientifolds in the cross-over region between the interior of the moduli space and its strictly asymptotic infinite-distance regions. Moreover, we also exhibit the existence of long-range axion valleys which, while not yet supporting slow-roll inflation, do show a flattened scalar potential from complex structure moduli backreaction and axion monodromy. We further illustrate how such regions hosting axion valleys may be obtained by using machine learning techniques.