Contracting Cosmologies and the Swampland

TL;DR

This paper explores how the swampland conjectures constrain contracting cosmologies with negative potentials, showing that the potential's slope must be sufficiently steep to be consistent with quantum gravity principles.

Contribution

It derives bounds on the potential's slope in contracting cosmologies using the swampland distance and entropy conjectures, providing new constraints on Ekpyrotic models.

Findings

The potential slope |V'|/|V| is bounded below by a constant of order one.

The bounds are consistent with the requirements for slow Ekpyrotic contraction.

A refined condition on the potential near local minima of negative potentials is established.

Abstract

We consider the cosmology obtained using scalar fields with a negative potential energy, such as employed to obtain an Ekpyrotic phase of contraction. Applying the covariant entropy bound to the tower of states dictated by the distance conjecture, we find that the relative slope of the potential $|V^{\prime}| / |V|$ is bounded from below by a constant of the order one in Planck units. This is consistent with the requirement to obtain slow Ekpyrotic contraction. We also derive a refined condition on the potential which holds near local minima of a negative potential.