Fate of $Z_2$ Symmetric Scalar Field

TL;DR

This paper investigates how a $Z_2$ symmetric scalar field's energy dissipates over time, revealing that strong enough coupling leads to efficient energy loss despite particle stability.

Contribution

It provides a detailed calculation of the dissipation rate of a $Z_2$ symmetric scalar field using the closed time path formalism, highlighting conditions for efficient energy dissipation.

Findings

Energy density can dissipate efficiently if coupling exceeds a critical value.

Scalar particle remains stable due to $Z_2$ symmetry despite dissipation.

Dissipation rate depends on the coupling strength and symmetry properties.

Abstract

The evolution of a coherently oscillating scalar field with $Z_2$ symmetry is studied in detail. We calculate the dissipation rate of the scalar field based on the closed time path formalism. Consequently, it is shown that the energy density of the coherent oscillation can be efficiently dissipated if the coupling constant is larger than the critical value, even though the scalar particle is stable due to the $Z_2$ symmetry.