The characteristic group of locally conformally product structures

Abstract

A compact manifold $M$ together with a Riemannian metric $h$ on its universal cover $\tilde{M}$ for which ${\pi }_1(M)$ acts by similarities is called a similarity structure. In the case where ${\pi }_1(M)\not\subset \mathrm{Isom}(\tilde{M},h)$ and $(\tilde{M},h)$ is reducible but not flat, this is a Locally Conformally Product (LCP) structure. The so-called characteristic group of these manifolds, which is a connected abelian Lie group, is the key to understand how they are built. We focus in this paper on the case where this group is simply connected, and give a description of the corresponding LCP structures. It appears that they are quotients of trivial ${\mathbb{R}}^p$-principal bundle over simply-connected manifolds by certain discrete subgroups of automorphisms. We prove that, conversely, it is always possible to endow such quotients with an LCP structure.

23 pages