Attractor behaviour in ELKO cosmology

TL;DR

This paper demonstrates that ELKO cosmology can have early-time stable attractors, including unique fast-roll inflation points, by redefining variables, addressing initial condition fine-tuning issues in cosmic acceleration models.

Contribution

It introduces a variable redefinition method showing ELKO cosmology admits early-time attractors, including a potential-independent fast-roll inflation point, which was absent in previous studies.

Findings

ELKO cosmology admits early-time stable fixed points.

Two sets of attractor points correspond to slow and fast-roll inflation.

Fast-roll inflation attractor is independent of potential form.

Abstract

We study the dynamics of ELKO in the context of accelerated phase of our universe. To avoid the fine tuning problem associated with the initial conditions, it is required that the dynamical equations lead to an early-time attractor. In the earlier works, it was shown that the dynamical equations containing ELKO fields do not lead to early-time stable fixed points. In this work, using redefinition of variables, we show that ELKO cosmology admits early-time stable fixed points. More interestingly, we show that ELKO cosmology admit two sets of attractor points corresponding to slow and fast-roll inflation. The fast-roll inflation attractor point is unqiue for ELKO as it is independent of the form of the potential. We also discuss the plausible choice of interaction terms in these two sets of attractor points and constraints on the coupling constant.