Dynamics of oscillating scalar field in thermal environment

TL;DR

This paper analyzes the complex dynamics of oscillating scalar fields in thermal environments, considering various effects like thermal corrections, dissipation, particle production, and soliton formation, which influence their evolution and abundance.

Contribution

It provides a detailed investigation of scalar field dynamics with thermal couplings, incorporating multiple effects that modify their behavior in cosmological scenarios.

Findings

Thermal corrections significantly alter the scalar potential.

Dissipation and particle production impact scalar field decay.

Multiple time scales govern the effectiveness of these effects.

Abstract

There often appear coherently oscillating scalar fields in particle physics motivated cosmological scenarios, which may have rich phenomenological consequences. Scalar fields should somehow interact with background thermal bath in order to decay into radiation at an appropriate epoch, but introducing some couplings to the scalar field makes the dynamics complicated. We investigate in detail the dynamics of a coherently oscillating scalar field, which has renormalizable couplings to another field interacting with thermal background. The scalar field dynamics and its resultant abundance are significantly modified by taking account of following effects : (1) thermal correction to the effective potential, (2) dissipation effect on the scalar field in thermal bath, (3) non-perturbative particle production events and (4) formation of non-topological solitons. There appear many time scales depending on the scalar mass, amplitude, couplings and the background temperature, which make the efficiencies of these effects non-trivial.