Out of the Swampland with Multifield Quintessence?

TL;DR

This paper investigates the stability and dynamics of multifield quintessence models with curved field space, showing they can produce late-time cosmic acceleration without flat potentials, potentially aligning with string theory constraints.

Contribution

It analyzes the fixed points and trajectories of two-field models with curved field space, highlighting conditions for stable acceleration compatible with swampland bounds.

Findings

Existence of non-geodesic trajectories with sharp turns enabling acceleration

Phase diagram analysis reveals conditions for late-time acceleration

Trajectories can match current universe state with proper initial conditions

Abstract

Multifield models with a curved field space have already been shown to be able to provide viable quintessence models for steep potentials that satisfy swampland bounds. The simplest dynamical systems of this type are obtained by coupling Einstein gravity to two scalar fields with a curved field space. In this paper we study the stability properties of the non-trivial fixed points of this dynamical system for a general functional dependence of the kinetic coupling function and the scalar potential. We find the existence of non-geodesic trajectories with a sharp turning rate in field space which can give rise to late-time cosmic acceleration with no need for flat potentials. In particular, we discuss the properties of the phase diagram of the system and the corresponding time evolution when varying the functional dependence of the kinetic coupling. Interestingly, upon properly tuning the initial conditions of the field values, we find trajectories that can describe the current state of the universe. This could represent a promising avenue to build viable quintessence models out of the swampland if they could be consistently embedded in explicit string constructions.