Spontaneous symmetry breaking on surface defects

Fuente: arXiv
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Main Authors: Cuomo, Gabriel, Zhang, Shuyu
Format: Preprint
Published: 2023
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author Cuomo, Gabriel
Zhang, Shuyu
author_facet Cuomo, Gabriel
Zhang, Shuyu
contents Coleman's theorem states that continuous internal symmetries cannot be spontaneously broken in two-dimensional quantum field theories (QFTs). In this work we consider surface (i.e. two-dimensional) defects in $d$-dimensional conformal field theories (CFTs) invariant under a continuous internal symmetry group $G$. We study under which conditions it is possible for a surface defect to break spontaneously a continuous internal symmetry. We find that spontaneous symmetry breaking (SSB) is impossible under reasonable assumptions on the defect Renormalization Group (RG) flow. Counterexamples are possible only for exotic RG flows, that do not terminate at a fixed-point. We discuss an example of this kind. We also illustrate our no-go result with an effective field theory analysis of generic defect RG flows. We find a generic weakly coupled defect universality class (with no SSB), where correlation functions decay logarithmically. Our analysis generalizes the recent discovery by Metlitski of the extraordinary-log boundary universality class in the $O(N)$ model.
format Preprint
id arxiv_https___arxiv_org_abs_2306_00085
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Spontaneous symmetry breaking on surface defects
Cuomo, Gabriel
Zhang, Shuyu
High Energy Physics - Theory
Statistical Mechanics
Strongly Correlated Electrons
Coleman's theorem states that continuous internal symmetries cannot be spontaneously broken in two-dimensional quantum field theories (QFTs). In this work we consider surface (i.e. two-dimensional) defects in $d$-dimensional conformal field theories (CFTs) invariant under a continuous internal symmetry group $G$. We study under which conditions it is possible for a surface defect to break spontaneously a continuous internal symmetry. We find that spontaneous symmetry breaking (SSB) is impossible under reasonable assumptions on the defect Renormalization Group (RG) flow. Counterexamples are possible only for exotic RG flows, that do not terminate at a fixed-point. We discuss an example of this kind. We also illustrate our no-go result with an effective field theory analysis of generic defect RG flows. We find a generic weakly coupled defect universality class (with no SSB), where correlation functions decay logarithmically. Our analysis generalizes the recent discovery by Metlitski of the extraordinary-log boundary universality class in the $O(N)$ model.
title Spontaneous symmetry breaking on surface defects
topic High Energy Physics - Theory
Statistical Mechanics
Strongly Correlated Electrons
url https://arxiv.org/abs/2306.00085