The Conformal Laplacian and Positive Scalar Curvature Metrics on Manifolds with Boundary

Fuente: arXiv
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Main Authors: Rosenberg, Steven, Ruberman, Daniel, Xu, Jie
Format: Preprint
Published: 2023
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author Rosenberg, Steven
Ruberman, Daniel
Xu, Jie
author_facet Rosenberg, Steven
Ruberman, Daniel
Xu, Jie
contents We give examples of spin $4$-manifolds with boundary $(M,\partial M)$ such that the boundary $\partial M$ has a positive scalar curvature metric which cannot be extended to a positive scalar curvature metric on $M$ with mean convex boundary. These manifolds have the equivalent analytic property that for any metric $g$ on $M$, the conformal Laplacian on $M$ with appropriate boundary conditions and the conformal Laplacian on $\partial M$ cannot both be positive. The obstruction to the positivity of the conformal Laplacians is given by a real-valued $ξ$-invariant associated to the APS theorem for the twisted Dirac operator. We use analytic techniques related to the prescribed scalar curvature problem in conformal geometry to directly treat metrics which are not a product near the boundary.
format Preprint
id arxiv_https___arxiv_org_abs_2302_05521
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Conformal Laplacian and Positive Scalar Curvature Metrics on Manifolds with Boundary
Rosenberg, Steven
Ruberman, Daniel
Xu, Jie
Differential Geometry
53C21 (primary), 35J66, 53C27, 58J05, 58J20 (secondary)
We give examples of spin $4$-manifolds with boundary $(M,\partial M)$ such that the boundary $\partial M$ has a positive scalar curvature metric which cannot be extended to a positive scalar curvature metric on $M$ with mean convex boundary. These manifolds have the equivalent analytic property that for any metric $g$ on $M$, the conformal Laplacian on $M$ with appropriate boundary conditions and the conformal Laplacian on $\partial M$ cannot both be positive. The obstruction to the positivity of the conformal Laplacians is given by a real-valued $ξ$-invariant associated to the APS theorem for the twisted Dirac operator. We use analytic techniques related to the prescribed scalar curvature problem in conformal geometry to directly treat metrics which are not a product near the boundary.
title The Conformal Laplacian and Positive Scalar Curvature Metrics on Manifolds with Boundary
topic Differential Geometry
53C21 (primary), 35J66, 53C27, 58J05, 58J20 (secondary)
url https://arxiv.org/abs/2302.05521