Band width and the Rosenberg index

TL;DR

This paper proves that closed spin manifolds with infinite KO-width or wide cube-like domains with non-trivial higher index have non-vanishing Rosenberg index, confirming a conjecture and extending previous results.

Contribution

It establishes a link between infinite KO-width and non-vanishing Rosenberg index, including a multi-dimensional generalization, confirming a conjecture by R. Zeidler.

Findings

Infinite KO-width implies non-vanishing Rosenberg index.

Extension to multi-dimensional cube-like domains.

Confirms R. Zeidler's conjecture.

Abstract

A Riemannian manifold is said to have infinite $\mathcal{KO}$-width if it admits an isometric immersion of an arbitrarily wide Riemannian band whose inward boundary has non-trivial higher index. In this paper we prove that if a closed spin manifold has inifinite $\mathcal{KO}$-width, then its Rosenberg index does not vanish. This gives a positive answer to a conjecture by R. Zeidler. We also prove its `multi-dimensional' generalization; if a closed spin manifold admit an isometric immersion of an arbitrarily wide cube-like domain whose lowest dimensional corner has non-trivial higher index, then the Rosenberg index of $M$ does not vanish.