On scale-separated supersymmetric AdS$_2$ flux vacua

Abstract: We argue that scale-separated AdS$_2$ vacua with at least two preserved supercharges cannot arise from flux compactifications in a regime of computational control. We deduce this by showing that the AdS$_2$ scale is parametrically of the same order as the tension of a fundamental BPS domain wall, which provides an upper bound on the UV cutoff. Since the latter does not need to be associated to any geometric scale, the argument excludes scale separation in a broader sense than what commonly considered. Our claim is exemplified by a bottom-up 2D supergravity analysis as well as top-down models from Type II flux compactifications.