Impurities with a cusp: general theory and 3d Ising

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Auteurs principaux: Cuomo, Gabriel, He, Yin-Chen, Komargodski, Zohar
Format: Preprint
Publié: 2024
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author Cuomo, Gabriel
He, Yin-Chen
Komargodski, Zohar
author_facet Cuomo, Gabriel
He, Yin-Chen
Komargodski, Zohar
contents In CFTs, the partition function of a line defect with a cusp depends logarithmically on the size of the line with an angle-dependent coefficient: the cusp anomalous dimension. In the first part of this work, we study the general properties of the cusp anomalous dimension. We relate the small cusp angle limit to the effective field theory of defect fusion, making predictions for the first couple of terms in the expansion. Using a concavity property of the cusp anomalous dimension we argue that the Casimir energy between a line defect and its orientation reversal is always negative ("opposites attract"). We use these results to determine the fusion algebra of Wilson lines in $\mathcal{N}=4$ SYM as well as pinning field defects in the Wilson-Fisher fixed points. In the second part of the paper we obtain nonperturbative numerical results for the cusp anomalous dimension of pinning field defects in the Ising model in $d=3$, using the recently developed fuzzy-sphere regularization. We also compute the pinning field cusp anomalous dimension in the $O(N)$ model at one-loop in the $\varepsilon$-expansion. Our results are in agreement with the general theory developed in the first part of the work, and we make several predictions for impurities in magnets.
format Preprint
id arxiv_https___arxiv_org_abs_2406_10186
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Impurities with a cusp: general theory and 3d Ising
Cuomo, Gabriel
He, Yin-Chen
Komargodski, Zohar
High Energy Physics - Theory
Strongly Correlated Electrons
In CFTs, the partition function of a line defect with a cusp depends logarithmically on the size of the line with an angle-dependent coefficient: the cusp anomalous dimension. In the first part of this work, we study the general properties of the cusp anomalous dimension. We relate the small cusp angle limit to the effective field theory of defect fusion, making predictions for the first couple of terms in the expansion. Using a concavity property of the cusp anomalous dimension we argue that the Casimir energy between a line defect and its orientation reversal is always negative ("opposites attract"). We use these results to determine the fusion algebra of Wilson lines in $\mathcal{N}=4$ SYM as well as pinning field defects in the Wilson-Fisher fixed points. In the second part of the paper we obtain nonperturbative numerical results for the cusp anomalous dimension of pinning field defects in the Ising model in $d=3$, using the recently developed fuzzy-sphere regularization. We also compute the pinning field cusp anomalous dimension in the $O(N)$ model at one-loop in the $\varepsilon$-expansion. Our results are in agreement with the general theory developed in the first part of the work, and we make several predictions for impurities in magnets.
title Impurities with a cusp: general theory and 3d Ising
topic High Energy Physics - Theory
Strongly Correlated Electrons
url https://arxiv.org/abs/2406.10186