Phase diagram of 1+1D Abelian-Higgs model and its critical point

TL;DR

This paper maps the phase diagram of the 1+1D Abelian-Higgs model, identifying a critical point with unique properties that separates Higgs and confined phases, revealing complex critical behavior.

Contribution

It provides the first detailed analysis of the phase diagram and critical point of the 1+1D Abelian-Higgs model on a lattice, highlighting novel critical phenomena.

Findings

Identification of a first order phase transition line

Discovery of a quantum critical point with mixed free fermion and boson characteristics

Evidence of unexpected phenomena beyond simple theoretical models

Abstract

We determine the phase diagram of the Abelian-Higgs model in one spatial dimension and time (1+1D) on a lattice. We identify a line of first order phase transitions separating the Higgs region from the confined one. This line terminates in a quantum critical point above which the two regions are connected by a smooth crossover. We analyze the critical point and find compelling evidences for its description as the product of two non-interacting systems, a massless free fermion and a massless free boson. However, we find also some surprizing results that cannot be explained by our simple picture, suggesting this newly discovered critical point to be an unusual one.