Cosmological α′-corrections from the functional renormalization group

• Main Authors: Ivano Basile, Alessia Platania
• Format: Article
• Language: English
• Published: SpringerOpen 2021-06-01
• Series: Journal of High Energy Physics
• Subjects: Cosmology of Theories beyond the SM; String Duality; Nonperturbative Effects; Renormalization Group
• Online Access: https://doi.org/10.1007/JHEP06(2021)045

Abstract We employ the techniques of the Functional Renormalization Group in string theory, in order to derive an effective mini-superspace action for cosmological backgrounds to all orders in the string scale α′. To this end, T-duality plays a crucial role, classifying all perturbative curvature corrections in terms of a single function of the Hubble parameter. The resulting renormalization group equations admit an exact, albeit non-analytic, solution in any spacetime dimension D, which is however incompatible with Einstein gravity at low energies. Within an E-expansion about D = 2, we also find an analytic solution which exhibits a non-Gaussian ultraviolet fixed point with positive Newton coupling, as well as an acceptable low-energy limit. Yet, within polynomial truncations of the full theory space, we find no evidence for an analog of this solution in D = 4. Finally, we comment on potential cosmological implications of our findings.