Sandwich operators and Einstein deformations of compact symmetric spaces related to Jordan algebras

Fuente: arXiv
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Auteurs principaux: Hall, Stuart James, Schwahn, Paul, Semmelmann, Uwe
Format: Preprint
Publié: 2024
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author Hall, Stuart James
Schwahn, Paul
Semmelmann, Uwe
author_facet Hall, Stuart James
Schwahn, Paul
Semmelmann, Uwe
contents We study the deformability of the symmetric Einstein metrics on the spaces $\mathrm{SU}(n)/\mathrm{SO}(n)$ and $\mathrm{SU}(2n)/\mathrm{Sp}(n)$, thereby concluding the problem to second order for all irreducible symmetric spaces. The obstruction integrals are calculated from invariant polynomials on certain Lie algebra representations. To aid the computation, we develop so-called sandwich operators for compact Lie algebras and relate them to quadratic Casimir operators. We also explain the source of the infinitesimal Einstein deformations on irreducible symmetric spaces, except for the complex Grassmannians, by exploring their relation to simple Jordan algebras. As an application we prove the nonlinear instability of most of the infinitesimally deformable irreducible compact symmetric spaces.
format Preprint
id arxiv_https___arxiv_org_abs_2412_08770
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sandwich operators and Einstein deformations of compact symmetric spaces related to Jordan algebras
Hall, Stuart James
Schwahn, Paul
Semmelmann, Uwe
Differential Geometry
Rings and Algebras
17B20, 17B60, 53C24, 53C25, 53C35
We study the deformability of the symmetric Einstein metrics on the spaces $\mathrm{SU}(n)/\mathrm{SO}(n)$ and $\mathrm{SU}(2n)/\mathrm{Sp}(n)$, thereby concluding the problem to second order for all irreducible symmetric spaces. The obstruction integrals are calculated from invariant polynomials on certain Lie algebra representations. To aid the computation, we develop so-called sandwich operators for compact Lie algebras and relate them to quadratic Casimir operators. We also explain the source of the infinitesimal Einstein deformations on irreducible symmetric spaces, except for the complex Grassmannians, by exploring their relation to simple Jordan algebras. As an application we prove the nonlinear instability of most of the infinitesimally deformable irreducible compact symmetric spaces.
title Sandwich operators and Einstein deformations of compact symmetric spaces related to Jordan algebras
topic Differential Geometry
Rings and Algebras
17B20, 17B60, 53C24, 53C25, 53C35
url https://arxiv.org/abs/2412.08770