Cosmic evolution of scalar fields with multiple vacua: generalized DBI and quintessence

TL;DR

This paper introduces a method to analyze the cosmic evolution of scalar fields, specifically generalized DBI and quintessence, with complex potentials, revealing differences in oscillation behavior due to their dynamics.

Contribution

It provides a new approach to rewrite equations of motion in autonomous form for arbitrary potentials, enabling detailed study of scalar field evolution with multiple vacua.

Findings

Scalars end up in either false or true vacuum.

Generalized DBI field oscillates more times than quintessence.

Faster speed reduces friction, increasing oscillations in DBI fields.

Abstract

We find a method to rewrite the equations of motion of scalar fields, generalized DBI field and quintessence, in the autonomous form for\emph{arbitrary} scalar potentials. With the aid of this method, we explore the cosmic evolution of generalized DBI field and quintessence with the potential of multiple vacua. Then we find that the scalars are always frozen in the false or true vacuum in the end. Compared to the evolution of quintessence, the generalized DBI field has more times of oscillations around the vacuum of the potential. The reason for this point is that, with the increasing of speed $\dot{\phi}$, the friction term of generalized DBI field is greatly decreased. Thus the generalized DBI field acquires more times of oscillations.