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Main Authors: Balacheff, Florent, Sardà, Teo Gil Moreno de Mora, Sabourau, Stéphane
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2407.07198
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author Balacheff, Florent
Sardà, Teo Gil Moreno de Mora
Sabourau, Stéphane
author_facet Balacheff, Florent
Sardà, Teo Gil Moreno de Mora
Sabourau, Stéphane
contents We prove that if an orientable 3-manifold $M$ admits a complete Riemannian metric whose scalar curvature is positive and has a subquadratic decay at infinity, then it decomposes as a (possibly infinite) connected sum of spherical manifolds and $\mathbb{S}^2 \times \mathbb{S}^1$ summands. This generalises a theorem of Gromov and Wang by using a different, more topological, approach. As a result, the manifold $M$ carries a complete Riemannian metric of uniformly positive scalar curvature, which partially answers a conjecture of Gromov. More generally, the topological decomposition holds without any scalar curvature assumption under a weaker condition on the filling discs of closed curves in the universal cover based on the notion of fill radius. Moreover, the decay rate of the scalar curvature is optimal in this decomposition theorem. Indeed, the manifold $\mathbb{R}^2 \times \mathbb{S}^1$ supports a complete metric of positive scalar curvature with exactly quadratic decay, but does not admit a decomposition as a connected sum.
format Preprint
id arxiv_https___arxiv_org_abs_2407_07198
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Complete 3-manifolds of positive scalar curvature with quadratic decay
Balacheff, Florent
Sardà, Teo Gil Moreno de Mora
Sabourau, Stéphane
Differential Geometry
Primary 53C23, Secondary 53C21
We prove that if an orientable 3-manifold $M$ admits a complete Riemannian metric whose scalar curvature is positive and has a subquadratic decay at infinity, then it decomposes as a (possibly infinite) connected sum of spherical manifolds and $\mathbb{S}^2 \times \mathbb{S}^1$ summands. This generalises a theorem of Gromov and Wang by using a different, more topological, approach. As a result, the manifold $M$ carries a complete Riemannian metric of uniformly positive scalar curvature, which partially answers a conjecture of Gromov. More generally, the topological decomposition holds without any scalar curvature assumption under a weaker condition on the filling discs of closed curves in the universal cover based on the notion of fill radius. Moreover, the decay rate of the scalar curvature is optimal in this decomposition theorem. Indeed, the manifold $\mathbb{R}^2 \times \mathbb{S}^1$ supports a complete metric of positive scalar curvature with exactly quadratic decay, but does not admit a decomposition as a connected sum.
title Complete 3-manifolds of positive scalar curvature with quadratic decay
topic Differential Geometry
Primary 53C23, Secondary 53C21
url https://arxiv.org/abs/2407.07198