Contracting cosmologies and the swampland

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′|/|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.

Swampland constraints on neutrino masses

“…We would like now to study whether the effective 3D potential is consistent with the dS conjecture as applied to AdS, as proposed in [21] (see also [49]) and discussed in the introduction. More concretely, we will assume that it is satisfied in 4d and check the constraints that appear from imposing that it is also satisfied in 3d, where it reads…”

“…Let us emphasize that we are analyzing the version of the dS conjecture proposed in [21,49] that contains the absolute value for the potential in the denominator in (4.4). This is specially motivated in AdS space [21].…”

Fundamental Physics, the Swampland of Effective Field Theory and Early Universe Cosmology

“…The fact that a negative sign arises is related to the fact that the ground state in superstring theory is typically AdS. The steepness of the potential is consistent with the de Sitter criterion, as a generalization of the derivation of the de Sitter constraint to the case of negative potentials has shown [28].…”

“…These criteria are for positive potentials. See[28] for a version of this criterion for negative potentials.…”

The robustness of slow contraction and the shape of the scalar field potential

“…However, if smoothing slow contraction is sourced by a scalar potential with M Pl |V ,φ /V | ≤ √ 6 (after the smooth FRW state is reached) and which is unbounded from below, the scalar field must explore exponentially large field ranges. Arguments from fundamental physics [1,3,7,15,16] suggest that an effective theory can only be consistent with quantum gravity if the scalar field explores a finite range of O(1) in reduced Planck units. For this reason, to prevent the scalar from rolling over field ranges O(1), we only consider potentials that are bounded from below.…”