Generalised Einstein metrics on Lie groups

Fuente: arXiv
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Main Authors: Cortés, Vicente, Freibert, Marco, Galdeano, Mateo
Format: Preprint
Published: 2024
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author Cortés, Vicente
Freibert, Marco
Galdeano, Mateo
author_facet Cortés, Vicente
Freibert, Marco
Galdeano, Mateo
contents We continue the systematic study of left-invariant generalised Einstein metrics on Lie groups initiated in arXiv:2206.01157. Our approach is based on a new reformulation of the corresponding algebraic system. For a fixed Lie algebra $\mathfrak{g}$, the unknowns of the system consist of a scalar product $g$ and a $3$-form $H$ on $\mathfrak{g}$ as well as a linear form $δ$ on $\mathfrak{g}\oplus\mathfrak{g}^*$. As in arXiv:2206.01157, the Lie bracket of $\mathfrak{g}$ is considered part of the unknowns. In the Riemannian case, we show that the generalised Einstein condition always reduces to the commutator ideal and we provide a full classification of solvable generalised Einstein Lie groups. In the Lorentzian case, under the additional assumption $δ=0$, we classify -- up to one case -- all almost Abelian generalised Einstein Lie groups. We then particularize to four dimensions and provide a full classification of generalised Einstein Riemannian Lie groups as well as generalised Einstein Lorentzian Lie groups with $δ=0$ and non-degenerate commutator ideal.
format Preprint
id arxiv_https___arxiv_org_abs_2407_16562
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Generalised Einstein metrics on Lie groups
Cortés, Vicente
Freibert, Marco
Galdeano, Mateo
Differential Geometry
53D18 (Primary) 53C25, 53C30 (Secondary)
We continue the systematic study of left-invariant generalised Einstein metrics on Lie groups initiated in arXiv:2206.01157. Our approach is based on a new reformulation of the corresponding algebraic system. For a fixed Lie algebra $\mathfrak{g}$, the unknowns of the system consist of a scalar product $g$ and a $3$-form $H$ on $\mathfrak{g}$ as well as a linear form $δ$ on $\mathfrak{g}\oplus\mathfrak{g}^*$. As in arXiv:2206.01157, the Lie bracket of $\mathfrak{g}$ is considered part of the unknowns. In the Riemannian case, we show that the generalised Einstein condition always reduces to the commutator ideal and we provide a full classification of solvable generalised Einstein Lie groups. In the Lorentzian case, under the additional assumption $δ=0$, we classify -- up to one case -- all almost Abelian generalised Einstein Lie groups. We then particularize to four dimensions and provide a full classification of generalised Einstein Riemannian Lie groups as well as generalised Einstein Lorentzian Lie groups with $δ=0$ and non-degenerate commutator ideal.
title Generalised Einstein metrics on Lie groups
topic Differential Geometry
53D18 (Primary) 53C25, 53C30 (Secondary)
url https://arxiv.org/abs/2407.16562