Phase Transitions in Quantum Field Theory

TL;DR

This paper explores phase transitions in quantum field theory by analyzing vacuum realignment mechanisms, employing a nonperturbative variational approach to understand how different phenomena like symmetry breaking occur.

Contribution

It introduces a nonperturbative, variational method for studying vacuum realignment and phase transitions in quantum field theory, including explicit construction of the physical vacuum.

Findings

Vacuum destabilization can occur via scalar expectation values or condensate mechanisms.

Phase transitions are characterized by discontinuities in classical order parameters.

The method provides a framework for analyzing nonperturbative phenomena in quantum field theory.

Abstract

We discuss here phase transitions in quantum field theory in the context of vacuum realignment through an explicit construction. Vacuum destabilisation may occur through a scalar attaining a nonzero expectation value, or through a condensate mechanism as in superconductivity and for chiral symmetry breaking, or by some other mechanism not taken here. Phase transition is defined as vacuum realignment with a discontinuity in some observables which correspond to the classical order parameters. The method is nonperturbative and variational, using equal time algebra and an ansatz for the construction of the physical vacuum.