Goldstone bosons at non-zero temperature

TL;DR

This paper investigates the behavior of Goldstone bosons at non-zero temperature using lattice simulations, revealing they persist as thermoparticles even in symmetry-restored phases, with implications for high-temperature systems.

Contribution

It provides non-perturbative evidence that Goldstone bosons become thermoparticles at finite temperature, demonstrating their continued existence beyond symmetry restoration.

Findings

Goldstone modes behave as screened, massless excitations at non-zero temperature

Goldstone bosons persist in symmetry-restored phases as thermoparticles

Spectral analysis reveals their dissipative properties

Abstract

Spontaneous symmetry breaking in quantum field theories at non-zero temperature still holds fundamental open questions, in particular what happens to vacuum Goldstone bosons when the temperature is increased. By investigating a complex scalar field theory on the lattice we demonstrate that Goldstone bosons at non-zero temperature behave like screened massless particle-like excitations, so-called thermoparticles, which continue to exist even in the symmetry-restored phase of the theory. We provide non-perturbative evidence for the functional form of the Goldstone mode's dissipative behaviour, and determine its corresponding spectral properties. Since the persistence of thermal Goldstone modes within symmetry-restored phases is predicted to be a model-independent characteristic, this has fundamental consequences for systems in which continuous symmetries are restored at high temperatures.