A special class of $k$-harmonic maps inducing calibrated fibrations

Fuente: arXiv
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Main Authors: Iliashenko, Anton, Karigiannis, Spiro
Format: Preprint
Published: 2023
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author Iliashenko, Anton
Karigiannis, Spiro
author_facet Iliashenko, Anton
Karigiannis, Spiro
contents We consider two special classes of $k$-harmonic maps between Riemannian manifolds which are related to calibrated geometry, satisfying a first order fully nonlinear PDE. The first is a special type of weakly conformal map $u \colon (L^k, g) \to (M^n, h)$ where $k \leq n$ and $α$ is a calibration $k$-form on $M$. Away from the critical set, the image is an $α$-calibrated submanifold of $M$. These were previously studied by Cheng-Karigiannis-Madnick when $α$ was associated to a vector cross product, but we clarify that such a restriction is unnecessary. The second, which is new, is a special type of weakly horizontally conformal map $u \colon (M^n, h) \to (L^k, g)$ where $n \geq k$ and $α$ is a calibration $(n-k)$-form on $M$. Away from the critical set, the fibres $u^{-1} \{ u(x) \}$ are $α$-calibrated submanifolds of $M$. We also review some previously established analytic results for the first class; we exhibit some explicit noncompact examples of the second class, where $(M, h)$ are the Bryant-Salamon manifolds with exceptional holonomy; we remark on the relevance of this new PDE to the Strominger-Yau-Zaslow conjecture for mirror symmetry in terms of special Lagrangian fibrations and to the $\mathrm{G}_2$ version by Gukov-Yau-Zaslow in terms of coassociative fibrations; and we present several open questions for future study.
format Preprint
id arxiv_https___arxiv_org_abs_2311_14074
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A special class of $k$-harmonic maps inducing calibrated fibrations
Iliashenko, Anton
Karigiannis, Spiro
Differential Geometry
53C38, 53C43, 58E20
We consider two special classes of $k$-harmonic maps between Riemannian manifolds which are related to calibrated geometry, satisfying a first order fully nonlinear PDE. The first is a special type of weakly conformal map $u \colon (L^k, g) \to (M^n, h)$ where $k \leq n$ and $α$ is a calibration $k$-form on $M$. Away from the critical set, the image is an $α$-calibrated submanifold of $M$. These were previously studied by Cheng-Karigiannis-Madnick when $α$ was associated to a vector cross product, but we clarify that such a restriction is unnecessary. The second, which is new, is a special type of weakly horizontally conformal map $u \colon (M^n, h) \to (L^k, g)$ where $n \geq k$ and $α$ is a calibration $(n-k)$-form on $M$. Away from the critical set, the fibres $u^{-1} \{ u(x) \}$ are $α$-calibrated submanifolds of $M$. We also review some previously established analytic results for the first class; we exhibit some explicit noncompact examples of the second class, where $(M, h)$ are the Bryant-Salamon manifolds with exceptional holonomy; we remark on the relevance of this new PDE to the Strominger-Yau-Zaslow conjecture for mirror symmetry in terms of special Lagrangian fibrations and to the $\mathrm{G}_2$ version by Gukov-Yau-Zaslow in terms of coassociative fibrations; and we present several open questions for future study.
title A special class of $k$-harmonic maps inducing calibrated fibrations
topic Differential Geometry
53C38, 53C43, 58E20
url https://arxiv.org/abs/2311.14074