The unmasking of thermal Goldstone bosons

Abstract

The problem of extracting the modes of Goldstone bosons from a thermal background is reconsidered in the framework of relativistic quantum field theory. It is shown that in the case of spontaneous breakdown of an internal bosonic symmetry a recently established decomposition of thermal correlation functions contains certain specific contributions which can be attributed to a particle of zero mass.

Comments: 7 pages, LaTeX; new and considerably strengthened results after Eq. (14); to appear in Phys. Rev. D