English

Scalar curvature comparison of rotationally symmetric sets

Differential Geometry 2024-10-29 v2

Abstract

Let (M,g)(M, g) be a compact 3-manifold with nonnegative scalar curvature Rg0R_g\geq 0. The boundary M\partial M is diffeomorphic to the boundary of a rotationally symmetric and weakly convex body Mˉ\bar{M} in R3\mathbb{R}^3. We call (Mˉ,δ)(\bar{M}, \delta) a model or a reference. Let HMH_{\partial M} and HˉM\bar{H}_{\partial M} be respectively the mean curvatures of M\partial M in (M,g)(M, g) and M\partial M in (Mˉ,δ)(\bar{M}, \delta), σ\sigma and σˉ\bar{\sigma} be the induced metric from gg and δ\delta. We show that for some classes of M\partial M, if HMHˉMH_{\partial M} \geq \bar{H}_{\partial M}, σσˉ\sigma \geq \bar{\sigma} and the dihedral angles at the nonsmooth part of M\partial M are no greater than the model, then MM is flat. We also generalize this result to the hyperbolic case and some spaces with S1\mathbb{S}^1-symmetry. Our approach is inspired by Gromov.

Keywords

Cite

@article{arxiv.2304.13152,
  title  = {Scalar curvature comparison of rotationally symmetric sets},
  author = {Xiaoxiang Chai and Gaoming Wang},
  journal= {arXiv preprint arXiv:2304.13152},
  year   = {2024}
}

Comments

The assumption $g\ge\delta$ is not needed in the case (c) of Theorem 1.2 with unchanged proof. We have removed the assumption in the version submitted to journals, but failed to update the arXiv promptly