An index theorem for Z/2-harmonic spinors branching along a graph

Fuente: arXiv
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Main Authors: Haydys, Andriy, Mazzeo, Rafe, Takahashi, Ryosuke
Format: Preprint
Published: 2023
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author Haydys, Andriy
Mazzeo, Rafe
Takahashi, Ryosuke
author_facet Haydys, Andriy
Mazzeo, Rafe
Takahashi, Ryosuke
contents We prove an index formula for the Dirac operator acting on two-valued spinors on a $3$-manifold $M$ which branch along a smoothly embedded graph $Σ\subset M$, and with respect to a boundary condition along $Σ$ inspired by an instance of this setting related to the deformation theory of $\mathbb Z_2$-harmonic spinors. When $Σ$ is a smooth embedded curve, this index vanishes; this was proved earlier by one of us, but the proof here is different and extends to the more general setting where $Σ$ also has vertices. We focus primarily on the Dirac operator itself, but also show how our results apply to more general twisted Dirac operators and to the closely related $\mathbb Z_2$ harmonic $1$-forms.
format Preprint
id arxiv_https___arxiv_org_abs_2310_15295
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle An index theorem for Z/2-harmonic spinors branching along a graph
Haydys, Andriy
Mazzeo, Rafe
Takahashi, Ryosuke
Differential Geometry
Analysis of PDEs
We prove an index formula for the Dirac operator acting on two-valued spinors on a $3$-manifold $M$ which branch along a smoothly embedded graph $Σ\subset M$, and with respect to a boundary condition along $Σ$ inspired by an instance of this setting related to the deformation theory of $\mathbb Z_2$-harmonic spinors. When $Σ$ is a smooth embedded curve, this index vanishes; this was proved earlier by one of us, but the proof here is different and extends to the more general setting where $Σ$ also has vertices. We focus primarily on the Dirac operator itself, but also show how our results apply to more general twisted Dirac operators and to the closely related $\mathbb Z_2$ harmonic $1$-forms.
title An index theorem for Z/2-harmonic spinors branching along a graph
topic Differential Geometry
Analysis of PDEs
url https://arxiv.org/abs/2310.15295