Fineness and smoothness of a KSBA moduli of marked cubic surfaces

Fuente: arXiv
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Hauptverfasser: Fang, Hanlong, Schaffler, Luca, Wu, Xian
Format: Preprint
Veröffentlicht: 2025
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author Fang, Hanlong
Schaffler, Luca
Wu, Xian
author_facet Fang, Hanlong
Schaffler, Luca
Wu, Xian
contents By work of Gallardo-Kerr-Schaffler, it is known that Naruki's compactification of the moduli space of marked cubic surfaces is isomorphic to the normalization of the Kollár, Shepherd-Barron, and Alexeev compactification parametrizing pairs $\left(S,\left(\frac{1}{9}+ε\right)D\right)$, with $D$ the sum of the $27$ marked lines on $S$, and their stable degenerations. In the current paper, we show that the normalization assumption is not necessary as we prove that this KSBA compactification is smooth. Additionally, we show it is a fine moduli space. This is done by studying the automorphisms and the $\mathbb{Q}$-Gorenstein obstructions of the stable pairs parametrized by it.
format Preprint
id arxiv_https___arxiv_org_abs_2501_05822
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fineness and smoothness of a KSBA moduli of marked cubic surfaces
Fang, Hanlong
Schaffler, Luca
Wu, Xian
Algebraic Geometry
14J10, 14D06, 14D23
By work of Gallardo-Kerr-Schaffler, it is known that Naruki's compactification of the moduli space of marked cubic surfaces is isomorphic to the normalization of the Kollár, Shepherd-Barron, and Alexeev compactification parametrizing pairs $\left(S,\left(\frac{1}{9}+ε\right)D\right)$, with $D$ the sum of the $27$ marked lines on $S$, and their stable degenerations. In the current paper, we show that the normalization assumption is not necessary as we prove that this KSBA compactification is smooth. Additionally, we show it is a fine moduli space. This is done by studying the automorphisms and the $\mathbb{Q}$-Gorenstein obstructions of the stable pairs parametrized by it.
title Fineness and smoothness of a KSBA moduli of marked cubic surfaces
topic Algebraic Geometry
14J10, 14D06, 14D23
url https://arxiv.org/abs/2501.05822