Integral elements of Okubo algebra and the E8-lattice

Fuente: arXiv
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Main Author: Corradetti, Daniele
Format: Preprint
Published: 2026
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author Corradetti, Daniele
author_facet Corradetti, Daniele
contents In this work we study the interplay between the Coxeter-Dickson $E_{8}$-order, the para-octonions, and the real Okubo algebra. We prove that the Coxeter-Dickson order remains closed for the para-octonionic product, so that one recovers a genuine $\mathbb{Z}$-integral system with underlying lattice $E_{8}$. Intriguingly, the Okubo product behaves in a different and more arithmetic way: it forces $\mathbb{Q}(\sqrt{3})$-coefficients and does not preserve the same $\mathbb{Z}$-order. After a diagonal $2$-adic scaling we obtain a closed $\mathbb{Z}[\sqrt{3}]$-order, whose direct metric shadow is a $2$-primary conductor sublattice of $E_{8}$, not $E_{8}$ itself. The lattice $E_{8}$ is recovered only by $2$-adic saturation, equivalently by gluing, and this recovery is metric-arithmetic rather than multiplicative.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09333
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Integral elements of Okubo algebra and the E8-lattice
Corradetti, Daniele
Rings and Algebras
In this work we study the interplay between the Coxeter-Dickson $E_{8}$-order, the para-octonions, and the real Okubo algebra. We prove that the Coxeter-Dickson order remains closed for the para-octonionic product, so that one recovers a genuine $\mathbb{Z}$-integral system with underlying lattice $E_{8}$. Intriguingly, the Okubo product behaves in a different and more arithmetic way: it forces $\mathbb{Q}(\sqrt{3})$-coefficients and does not preserve the same $\mathbb{Z}$-order. After a diagonal $2$-adic scaling we obtain a closed $\mathbb{Z}[\sqrt{3}]$-order, whose direct metric shadow is a $2$-primary conductor sublattice of $E_{8}$, not $E_{8}$ itself. The lattice $E_{8}$ is recovered only by $2$-adic saturation, equivalently by gluing, and this recovery is metric-arithmetic rather than multiplicative.
title Integral elements of Okubo algebra and the E8-lattice
topic Rings and Algebras
url https://arxiv.org/abs/2605.09333