Critical or tricritical point in mixed-action SU(2) lattice gauge theory?

TL;DR

This paper investigates the nature of the phase transition in mixed-action SU(2) lattice gauge theory, providing evidence that the endpoint of the first-order transition line is a tricritical point rather than a standard critical point, with implications for the phase diagram.

Contribution

The study offers new evidence supporting the tricritical nature of the endpoint in SU(2) lattice gauge theory, challenging previous assumptions of a simple critical point.

Findings

Supports the tricritical point hypothesis for the transition endpoint

Suggests the transition extends as a second-order transition beyond the endpoint

Indicates the transition may be the same as the finite-temperature transition

Abstract

An analysis of scaling along the first-order bulk transition line in fundamental-adjoint SU(2) lattice gauge theory strongly supports the first-order endpoint being a tricritical point, and is inconsistent with it being an ordinary critical point as is usually assumed. If tricritical, the transition must continue from the endpoint further into the phase diagram as a second-order bulk transition and extend to and beyond the Wilson axis. Observations indicate that this is most likely the same transition that has been traditionally considered a finite-temperature transition.