String tension between de Sitter vacua and curvature corrections

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 alpha'. The functional renormalization group, in conjunction with the strong constraints imposed by T-duality, allows us to derive cosmological effective actions to all orders in alpha' while avoiding truncations of the theory space. We show that the resulting higher-derivative alpha'-corrections forbid the existence of de Sitter vacua, at least in regimes where string-loop corrections can be neglected. Our findings thus support the no-de Sitter swampland conjecture in the presence of all-order effects in alpha'.

Automated summary

By utilizing the functional renormalization group and constraints of T-duality, we have derived cosmological effective actions to all orders in alpha', avoiding truncations of the theory space. Our findings show that higher-derivative alpha' corrections prohibit the existence of de Sitter vacua, supporting the no-de Sitter swampland conjecture in the presence of all-order effects in alpha'.