The Chow ring of the moduli space of degree $2$ quasi-polarized K3 surfaces

Fuente: arXiv
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Autores principales: Canning, Samir, Oprea, Dragos, Pandharipande, Rahul
Formato: Preprint
Publicado: 2023
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author Canning, Samir
Oprea, Dragos
Pandharipande, Rahul
author_facet Canning, Samir
Oprea, Dragos
Pandharipande, Rahul
contents We study the Chow ring with rational coefficients of the moduli space $\mathcal F_{2}$ of quasi-polarized $K3$ surfaces of degree $2$. We find generators, relations, and calculate the Chow Betti numbers. The highest nonvanishing Chow group is $\mathsf A^{17}(\mathcal F_2)\cong {\mathbb{Q}}$. We prove that the Chow ring consists of tautological classes and is isomorphic to the even cohomology. The Chow ring is not generated by divisors and does not satisfy duality with respect to the pairing into $\mathsf A^{17}(\mathcal F_2)$. The kernel of the pairing is a 1-dimensional subspace of $\mathsf{A}^{9}(\mathcal F_2)$ which we calculate explicitly. In the appendix, we revisit Kirwan-Lee's calculation of the Poincaré polynomial of $\mathcal{F}_2$.
format Preprint
id arxiv_https___arxiv_org_abs_2307_09284
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Chow ring of the moduli space of degree $2$ quasi-polarized K3 surfaces
Canning, Samir
Oprea, Dragos
Pandharipande, Rahul
Algebraic Geometry
14C15, 14C17, 14J28
We study the Chow ring with rational coefficients of the moduli space $\mathcal F_{2}$ of quasi-polarized $K3$ surfaces of degree $2$. We find generators, relations, and calculate the Chow Betti numbers. The highest nonvanishing Chow group is $\mathsf A^{17}(\mathcal F_2)\cong {\mathbb{Q}}$. We prove that the Chow ring consists of tautological classes and is isomorphic to the even cohomology. The Chow ring is not generated by divisors and does not satisfy duality with respect to the pairing into $\mathsf A^{17}(\mathcal F_2)$. The kernel of the pairing is a 1-dimensional subspace of $\mathsf{A}^{9}(\mathcal F_2)$ which we calculate explicitly. In the appendix, we revisit Kirwan-Lee's calculation of the Poincaré polynomial of $\mathcal{F}_2$.
title The Chow ring of the moduli space of degree $2$ quasi-polarized K3 surfaces
topic Algebraic Geometry
14C15, 14C17, 14J28
url https://arxiv.org/abs/2307.09284