Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry

Abstract By adapting previously known arguments concerning Ricci flow and the c-theorem, we give a direct proof that in a two-dimensional sigma-model with compact target space, scale invariance implies conformal invariance in perturbation theory. This argument, which applies to a general sigma-model...

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Main Authors: Georgios Papadopoulos, Edward Witten
Format: Article
Language:English
Published: SpringerOpen 2025-03-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP03(2025)056
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author Georgios Papadopoulos
Edward Witten
author_facet Georgios Papadopoulos
Edward Witten
author_sort Georgios Papadopoulos
collection DOAJ
description Abstract By adapting previously known arguments concerning Ricci flow and the c-theorem, we give a direct proof that in a two-dimensional sigma-model with compact target space, scale invariance implies conformal invariance in perturbation theory. This argument, which applies to a general sigma-model constructed with a target space metric and B-field, is in accord with a more general proof in the literature that applies to arbitrary two-dimensional quantum field theories. Models with extended supersymmetry and a B-field are known to provide interesting test cases for the relation between scale invariance and conformal invariance in sigma-model perturbation theory. We give examples showing that in such models, the obstructions to conformal invariance suggested by general arguments can actually occur in models with target spaces that are not compact or complete. Thus compactness of the target space, or at least a suitable condition of completeness, is necessary as well as sufficient to ensure that scale invariance implies conformal invariance in models of this type.
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spelling doaj-art-d5f095a89395482e9becddf8244f912b2025-08-20T02:16:06ZengSpringerOpenJournal of High Energy Physics1029-84792025-03-012025313110.1007/JHEP03(2025)056Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetryGeorgios Papadopoulos0Edward Witten1Department of Mathematics, King’s College LondonSchool of Natural Sciences, Institute for Advanced StudyAbstract By adapting previously known arguments concerning Ricci flow and the c-theorem, we give a direct proof that in a two-dimensional sigma-model with compact target space, scale invariance implies conformal invariance in perturbation theory. This argument, which applies to a general sigma-model constructed with a target space metric and B-field, is in accord with a more general proof in the literature that applies to arbitrary two-dimensional quantum field theories. Models with extended supersymmetry and a B-field are known to provide interesting test cases for the relation between scale invariance and conformal invariance in sigma-model perturbation theory. We give examples showing that in such models, the obstructions to conformal invariance suggested by general arguments can actually occur in models with target spaces that are not compact or complete. Thus compactness of the target space, or at least a suitable condition of completeness, is necessary as well as sufficient to ensure that scale invariance implies conformal invariance in models of this type.https://doi.org/10.1007/JHEP03(2025)056Field Theories in Lower DimensionsScale and Conformal SymmetriesSigma ModelsConformal Field Models in String Theory
spellingShingle Georgios Papadopoulos
Edward Witten
Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
Journal of High Energy Physics
Field Theories in Lower Dimensions
Scale and Conformal Symmetries
Sigma Models
Conformal Field Models in String Theory
title Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
title_full Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
title_fullStr Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
title_full_unstemmed Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
title_short Scale and conformal invariance in 2d σ-models, with an application to $$\mathcal{N}$$ = 4 supersymmetry
title_sort scale and conformal invariance in 2d σ models with an application to mathcal n 4 supersymmetry
topic Field Theories in Lower Dimensions
Scale and Conformal Symmetries
Sigma Models
Conformal Field Models in String Theory
url https://doi.org/10.1007/JHEP03(2025)056
work_keys_str_mv AT georgiospapadopoulos scaleandconformalinvariancein2dsmodelswithanapplicationtomathcaln4supersymmetry
AT edwardwitten scaleandconformalinvariancein2dsmodelswithanapplicationtomathcaln4supersymmetry