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Main Authors: Okada, Masaki, Watari, Taizan
Format: Preprint
Published: 2023
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Online Access:https://arxiv.org/abs/2306.10282
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_version_ 1866914650984022016
author Okada, Masaki
Watari, Taizan
author_facet Okada, Masaki
Watari, Taizan
contents CM-type projective varieties X of complex dimension n are characterized by their CM-type rational Hodge structures on the cohomology groups. One may impose such a condition in a weakest form when the canonical bundle of X is trivial; the rational Hodge structure on the level-n subspace of $H^n(X;Q)$ is required to be of CM-type. This brief note addresses the question whether this weak condition implies that the Hodge structure on the entire $H^\ast(X;Q)$ is of CM-type. We study in particular abelian varieties when the dimension of the level-n subspace is two or four, and K3 $\times T^2$. It turns out that the answer is affirmative. Moreover, such an abelian variety is always isogenous to a product of CM-type elliptic curves or abelian surfaces. This extends a result of Shioda and Mitani in 1974.
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id arxiv_https___arxiv_org_abs_2306_10282
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A note on varieties of weak CM-type
Okada, Masaki
Watari, Taizan
Algebraic Geometry
High Energy Physics - Theory
CM-type projective varieties X of complex dimension n are characterized by their CM-type rational Hodge structures on the cohomology groups. One may impose such a condition in a weakest form when the canonical bundle of X is trivial; the rational Hodge structure on the level-n subspace of $H^n(X;Q)$ is required to be of CM-type. This brief note addresses the question whether this weak condition implies that the Hodge structure on the entire $H^\ast(X;Q)$ is of CM-type. We study in particular abelian varieties when the dimension of the level-n subspace is two or four, and K3 $\times T^2$. It turns out that the answer is affirmative. Moreover, such an abelian variety is always isogenous to a product of CM-type elliptic curves or abelian surfaces. This extends a result of Shioda and Mitani in 1974.
title A note on varieties of weak CM-type
topic Algebraic Geometry
High Energy Physics - Theory
url https://arxiv.org/abs/2306.10282