Index invariants and Eta invariants determine Differential KO theory in degrees that are multiples of 8

Fuente: arXiv
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Autore principale: Su, Tan
Natura: Preprint
Pubblicazione: 2025
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author Su, Tan
author_facet Su, Tan
contents Sullivan--Simons developed a Cheeger--Simons differential character analogue for degree (0 mod 2) differential K-theory, giving a complete set of numerical invariants that determine a complex vector bundle with unitary connection on a base manifold X, up to Chern--Simons equivalence of the connection. In this paper we develop a degree (0 mod 8) differential KO-analogue. Namely, given a real vector bundle with orthogonal connection, we construct R/Z -valued eta-invariants in the context of Atiyah--Patodi--Singer and Z2 Atiyah--Singer index invariants that completely determine differential KO-theory in degree (0 mod 8); we call this the differential KO-character. In the second part, for a Riemannian submersion X to B with closed 8k-dimensional spin fibers, we develop two family index theorems in differential KO -theory: one in the differential KO -character model and one in the structured-bundle model. The fact that these two pushforwards agree follows from the Bismut--Cheeger adiabatic limit theorem, providing a new interpretation of that result.
format Preprint
id arxiv_https___arxiv_org_abs_2511_19904
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Index invariants and Eta invariants determine Differential KO theory in degrees that are multiples of 8
Su, Tan
K-Theory and Homology
Algebraic Topology
Differential Geometry
Sullivan--Simons developed a Cheeger--Simons differential character analogue for degree (0 mod 2) differential K-theory, giving a complete set of numerical invariants that determine a complex vector bundle with unitary connection on a base manifold X, up to Chern--Simons equivalence of the connection. In this paper we develop a degree (0 mod 8) differential KO-analogue. Namely, given a real vector bundle with orthogonal connection, we construct R/Z -valued eta-invariants in the context of Atiyah--Patodi--Singer and Z2 Atiyah--Singer index invariants that completely determine differential KO-theory in degree (0 mod 8); we call this the differential KO-character. In the second part, for a Riemannian submersion X to B with closed 8k-dimensional spin fibers, we develop two family index theorems in differential KO -theory: one in the differential KO -character model and one in the structured-bundle model. The fact that these two pushforwards agree follows from the Bismut--Cheeger adiabatic limit theorem, providing a new interpretation of that result.
title Index invariants and Eta invariants determine Differential KO theory in degrees that are multiples of 8
topic K-Theory and Homology
Algebraic Topology
Differential Geometry
url https://arxiv.org/abs/2511.19904