Dirac-harmonic maps with trivial index

Fuente: arXiv
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Autores principales: Jost, Jürgen, Sun, Linlin, Zhu, Jingyong
Formato: Preprint
Publicado: 2022
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author Jost, Jürgen
Sun, Linlin
Zhu, Jingyong
author_facet Jost, Jürgen
Sun, Linlin
Zhu, Jingyong
contents For a homotopy class $[u]$ of maps between a closed Riemannian manifold $M$ and a general manifold $N$, we want to find a Dirac-harmonic map with the map component in the given homotopy class. Most known results require the index to be nontrivial. When the index is trivial, the few known results are all constructive and produce uncoupled solutions. In this paper, we define a new quantity. As a byproduct of proving the homotopy invariance of this new quantity, we find a new simple proof for the fact that all Dirac-harmonic spheres in surfaces are uncoupled. More importantly, by using the homotopy invariance of this new quantity, we prove the existence of Dirac-harmonic maps from manifolds in the trivial index case. In particular, when the domain is a closed Riemann surface, we prove the short-time existence of the $α$-Dirac-harmonic map flow in the trivial index case. Together with the density of the minimal kernel, we get an existence result for Dirac-harmonic maps from closed Riemann surfaces to Kähler manifolds, which extends the previous result of the first and third authors. This establishes a general existence theory for Dirac-harmonic maps in the context of trivial index.
format Preprint
id arxiv_https___arxiv_org_abs_2209_04106
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Dirac-harmonic maps with trivial index
Jost, Jürgen
Sun, Linlin
Zhu, Jingyong
Differential Geometry
Analysis of PDEs
For a homotopy class $[u]$ of maps between a closed Riemannian manifold $M$ and a general manifold $N$, we want to find a Dirac-harmonic map with the map component in the given homotopy class. Most known results require the index to be nontrivial. When the index is trivial, the few known results are all constructive and produce uncoupled solutions. In this paper, we define a new quantity. As a byproduct of proving the homotopy invariance of this new quantity, we find a new simple proof for the fact that all Dirac-harmonic spheres in surfaces are uncoupled. More importantly, by using the homotopy invariance of this new quantity, we prove the existence of Dirac-harmonic maps from manifolds in the trivial index case. In particular, when the domain is a closed Riemann surface, we prove the short-time existence of the $α$-Dirac-harmonic map flow in the trivial index case. Together with the density of the minimal kernel, we get an existence result for Dirac-harmonic maps from closed Riemann surfaces to Kähler manifolds, which extends the previous result of the first and third authors. This establishes a general existence theory for Dirac-harmonic maps in the context of trivial index.
title Dirac-harmonic maps with trivial index
topic Differential Geometry
Analysis of PDEs
url https://arxiv.org/abs/2209.04106