The gap phenomenon for conformally related Einstein metrics

Fuente: arXiv
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Autori principali: Gregorovič, Jan, Šilhan, Josef
Natura: Preprint
Pubblicazione: 2024
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author Gregorovič, Jan
Šilhan, Josef
author_facet Gregorovič, Jan
Šilhan, Josef
contents We determine the submaximal dimensions of the spaces of almost Einstein scales and normal conformal Killing fields for connected conformal manifolds. The results depend on the signature and dimension $n$ of the conformally nonflat conformal manifold. In the Riemannian case, these two dimensions are at most $n-3$ and $\frac{(n-4)(n-3)}{2}$, respectively. In the Lorentzian case, these two dimensions are at most $n-2$ and $\frac{(n-3)(n-2)}{2}$, respectively. In the remaining signatures, these two dimensions are at most $n-1$ and $\frac{(n-2)(n-1)}{2}$, respectively. This upper bound is sharp and to realize examples of submaximal dimensions, we first provide them directly in dimension 4. In higher dimensions, we construct the submaximal examples as the (warped) product of the (pseudo)-Euclidean base of dimension $n-4$ with one of the 4-dimensional submaximal examples.
format Preprint
id arxiv_https___arxiv_org_abs_2401_03909
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The gap phenomenon for conformally related Einstein metrics
Gregorovič, Jan
Šilhan, Josef
Differential Geometry
58J70, 53C18, 53C25, 58J60
We determine the submaximal dimensions of the spaces of almost Einstein scales and normal conformal Killing fields for connected conformal manifolds. The results depend on the signature and dimension $n$ of the conformally nonflat conformal manifold. In the Riemannian case, these two dimensions are at most $n-3$ and $\frac{(n-4)(n-3)}{2}$, respectively. In the Lorentzian case, these two dimensions are at most $n-2$ and $\frac{(n-3)(n-2)}{2}$, respectively. In the remaining signatures, these two dimensions are at most $n-1$ and $\frac{(n-2)(n-1)}{2}$, respectively. This upper bound is sharp and to realize examples of submaximal dimensions, we first provide them directly in dimension 4. In higher dimensions, we construct the submaximal examples as the (warped) product of the (pseudo)-Euclidean base of dimension $n-4$ with one of the 4-dimensional submaximal examples.
title The gap phenomenon for conformally related Einstein metrics
topic Differential Geometry
58J70, 53C18, 53C25, 58J60
url https://arxiv.org/abs/2401.03909