Title: Cosmological α′-corrections from the functional renormalization group

Abstract: Higher-derivative corrections to cosmological effective actions in string theory are largely constrained by T-duality, but have been computed hitherto only to the first few orders in the string scale α′. The functional renormalization group, in conjunction with the strong constraints imposed by T-duality, can be used to derive cosmological effective actions to all orders in α′ while avoiding “truncations” of the theory space. We exploit the resulting mini-superspace effective actions to investigate the existence of (non-perturbative) de Sitter vacua. Our findings support the no-de Sitter swampland conjecture in the presence of all-order effects in α′.