Lefschetz decompositions of Kudla-Millson theta functions

Fuente: arXiv
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Main Authors: Bruinier, Jan Hendrik, Zuffetti, Riccardo
Format: Preprint
Published: 2024
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author Bruinier, Jan Hendrik
Zuffetti, Riccardo
author_facet Bruinier, Jan Hendrik
Zuffetti, Riccardo
contents In the 80's Kudla and Millson introduced a theta function in two variables. It behaves as a Siegel modular form with respect to the first variable, and is a closed differential form on an orthogonal Shimura variety with respect to the other variable. We prove that the Lefschetz decomposition of the cohomology class of that theta function is also its modular decomposition in Eisenstein, Klingen and cuspidal parts. We also show that the image of the Kudla-Millson lift is contained in the primitive cohomology of X. As an application, we deduce dimension formulas for the cohomology of X in low degree. Our results cover the cases of moduli spaces of compact hyperkähler manifolds.
format Preprint
id arxiv_https___arxiv_org_abs_2406_19921
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Lefschetz decompositions of Kudla-Millson theta functions
Bruinier, Jan Hendrik
Zuffetti, Riccardo
Number Theory
Algebraic Geometry
11F27 (Primary), 14J10, 11F46, 14C25 (Secondary)
In the 80's Kudla and Millson introduced a theta function in two variables. It behaves as a Siegel modular form with respect to the first variable, and is a closed differential form on an orthogonal Shimura variety with respect to the other variable. We prove that the Lefschetz decomposition of the cohomology class of that theta function is also its modular decomposition in Eisenstein, Klingen and cuspidal parts. We also show that the image of the Kudla-Millson lift is contained in the primitive cohomology of X. As an application, we deduce dimension formulas for the cohomology of X in low degree. Our results cover the cases of moduli spaces of compact hyperkähler manifolds.
title Lefschetz decompositions of Kudla-Millson theta functions
topic Number Theory
Algebraic Geometry
11F27 (Primary), 14J10, 11F46, 14C25 (Secondary)
url https://arxiv.org/abs/2406.19921