Dark Energy from Inspiraling in Field Space

TL;DR

This paper presents exact solutions in a two-field cosmological model demonstrating multi-field dark energy with large turning trajectories, leading to accelerated expansion, and explores the specific scalar potentials compatible with these solutions.

Contribution

It provides the first exact analytical solutions for multi-field dark energy models with large turning trajectories in field space, especially in Poincaré-disk geometry.

Findings

Trajectories spiral inward toward the Poincaré disk center.

Scalar potential form is compatible with a hidden symmetry.

Solutions demonstrate accelerated expansion with rotationally invariant potentials.

Abstract

We find an exact solution of the equations of motion of a two-field cosmological model, which realizes multi-field dark energy. The latter is characterized by field-space trajectories with turning rates that are always large. We study a class of two-field models and show that it is possible to have such trajectories, giving accelerated space-time expansion, even when the scalar potential preserves the rotational invariance of the field-space metric. For the case of Poincar\'e-disk field space, we derive the form of the scalar potential compatible with such background solutions and, furthermore, we find the exact solutions analytically. Their field-space trajectories are spirals inward, toward the center of the Poincar\'e disk. Interestingly, the functional form of the relevant scalar potential is compatible with a certain hidden symmetry, although the latter is broken by the presence of a constant term.