Extremal fixed points and Diophantine equations

Abstract The coupling constants of fixed points in the ϵ expansion at one loop are known to satisfy a quadratic bound due to Rychkov and Stergiou. We refer to fixed points that saturate this bound as extremal fixed points. The theories which contain such fixed points are those which undergo a saddle...

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Main Authors: Christopher P. Herzog, Christian B. Jepsen, Hugh Osborn, Yaron Oz
Format: Article
Language:English
Published: SpringerOpen 2024-09-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP09(2024)165
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author Christopher P. Herzog
Christian B. Jepsen
Hugh Osborn
Yaron Oz
author_facet Christopher P. Herzog
Christian B. Jepsen
Hugh Osborn
Yaron Oz
author_sort Christopher P. Herzog
collection DOAJ
description Abstract The coupling constants of fixed points in the ϵ expansion at one loop are known to satisfy a quadratic bound due to Rychkov and Stergiou. We refer to fixed points that saturate this bound as extremal fixed points. The theories which contain such fixed points are those which undergo a saddle-node bifurcation, entailing the presence of a marginal operator. Among bifundamental theories, a few examples of infinite families of such theories are known. A necessary condition for extremality is that the sizes of the factors of the symmetry group of a given theory satisfy a specific Diophantine equation, given in terms of what we call the extremality polynomial. In this work we study such Diophantine equations and employ a combination of rigorous and probabilistic estimates to argue that these infinite families constitute rare exceptions. The Pell equation, Falting’s theorem, Siegel’s theorem, and elliptic curves figure prominently in our analysis. In the cases we study here, more generic classes of multi-fundamental theories saturate the Rychkov-Stergiou bound only in sporadic cases or in limits where they degenerate into simpler known examples.
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spelling doaj-art-2c680f2f70674293b792f5f760b7c8132024-12-08T12:14:27ZengSpringerOpenJournal of High Energy Physics1029-84792024-09-012024915310.1007/JHEP09(2024)165Extremal fixed points and Diophantine equationsChristopher P. Herzog0Christian B. Jepsen1Hugh Osborn2Yaron Oz3Department of Mathematics, King’s College LondonSchool of Physics, Korea Institute for Advanced StudyDepartment of Applied Mathematics and Theoretical Physics, University of CambridgeSchool of Physics and Astronomy, Tel Aviv UniversityAbstract The coupling constants of fixed points in the ϵ expansion at one loop are known to satisfy a quadratic bound due to Rychkov and Stergiou. We refer to fixed points that saturate this bound as extremal fixed points. The theories which contain such fixed points are those which undergo a saddle-node bifurcation, entailing the presence of a marginal operator. Among bifundamental theories, a few examples of infinite families of such theories are known. A necessary condition for extremality is that the sizes of the factors of the symmetry group of a given theory satisfy a specific Diophantine equation, given in terms of what we call the extremality polynomial. In this work we study such Diophantine equations and employ a combination of rigorous and probabilistic estimates to argue that these infinite families constitute rare exceptions. The Pell equation, Falting’s theorem, Siegel’s theorem, and elliptic curves figure prominently in our analysis. In the cases we study here, more generic classes of multi-fundamental theories saturate the Rychkov-Stergiou bound only in sporadic cases or in limits where they degenerate into simpler known examples.https://doi.org/10.1007/JHEP09(2024)165Global SymmetriesRenormalization GroupScale and Conformal SymmetriesDifferential and Algebraic Geometry
spellingShingle Christopher P. Herzog
Christian B. Jepsen
Hugh Osborn
Yaron Oz
Extremal fixed points and Diophantine equations
Journal of High Energy Physics
Global Symmetries
Renormalization Group
Scale and Conformal Symmetries
Differential and Algebraic Geometry
title Extremal fixed points and Diophantine equations
title_full Extremal fixed points and Diophantine equations
title_fullStr Extremal fixed points and Diophantine equations
title_full_unstemmed Extremal fixed points and Diophantine equations
title_short Extremal fixed points and Diophantine equations
title_sort extremal fixed points and diophantine equations
topic Global Symmetries
Renormalization Group
Scale and Conformal Symmetries
Differential and Algebraic Geometry
url https://doi.org/10.1007/JHEP09(2024)165
work_keys_str_mv AT christopherpherzog extremalfixedpointsanddiophantineequations
AT christianbjepsen extremalfixedpointsanddiophantineequations
AT hughosborn extremalfixedpointsanddiophantineequations
AT yaronoz extremalfixedpointsanddiophantineequations