Supercritical String Cosmology drains the Swampland

TL;DR

This paper explores how non-critical string cosmology modifies the Swampland Conjectures, affecting entropy bounds and the weak gravity conjecture, with implications for de Sitter phases and scalar potentials.

Contribution

It demonstrates that non-critical string cosmology can reconcile the Swampland Conjectures with de Sitter phases and scalar potentials, providing new insights into string cosmology.

Findings

Modified FSC & SSC in non-critical string cosmology.

Restoration of entropy bounds in de Sitter phases.

Saturation of the WGC for scalar potentials in supercritical strings.

Abstract

The First and Second Swampland Conjectures (FSC & SSC) are substantially modified in non-critical string cosmology, in which cosmic time is identified with the time-like Liouville mode of the supercritical string. In this scenario the Friedmann equation receives additional contributions due to the non-criticality of the string. These are potentially important when one seeks to apply the Bousso bound for the entropy of states that may become light as the dilaton takes on trans-Planckian values, as in a de Sitter phase, and restore consistency with the FSC and in at least some cases also the SSC. The weak gravity conjecture (WGC) for scalar potentials is saturated in the supercritical string scenarios discussed in this work, but only if one uses the dilaton as appears in the string effective action, with a kinetic term that is not canonically normalised. In the case of a non-critical Starobinsky potential, the WGC is satisfied by both the canonically-normalised dilaton and the dilaton used in the string effective action.