K-stability of pointless del Pezzo surfaces and Fano 3-folds

Fuente: arXiv
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Autori principali: Abban, Hamid, Cheltsov, Ivan, Kishimoto, Takashi, Mangolte, Frederic
Natura: Preprint
Pubblicazione: 2024
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author Abban, Hamid
Cheltsov, Ivan
Kishimoto, Takashi
Mangolte, Frederic
author_facet Abban, Hamid
Cheltsov, Ivan
Kishimoto, Takashi
Mangolte, Frederic
contents We explore connections between existence of $\Bbbk$-rational points for Fano varieties defined over $\Bbbk$, a subfield of $\mathbb{C}$, and existence of Kähler-Einstein metrics on their geometric models. First, we show that geometric models of del Pezzo surfaces with at worst quotient singularities defined over $\Bbbk\subset\mathbb{C}$ admit (orbifold) Kähler--Einstein metrics if they do not have $\Bbbk$-rational points. Then we prove the same result for smooth Fano 3-folds with 8 exceptions. Consequently, we explicitly describe several families of pointless Fano 3-folds whose geometric models admit Kähler-Einstein metrics. In particular, we obtain new examples of prime Fano 3-folds of genus $12$ that admit Kähler--Einstein metrics. Our result can also be used to prove existence of rational points for certain Fano varieties, for example for any smooth Fano 3-fold over $\Bbbk\subset\mathbb{C}$ whose geometric model is strictly K-semistable.
format Preprint
id arxiv_https___arxiv_org_abs_2411_00767
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle K-stability of pointless del Pezzo surfaces and Fano 3-folds
Abban, Hamid
Cheltsov, Ivan
Kishimoto, Takashi
Mangolte, Frederic
Algebraic Geometry
14J45, 32Q20
We explore connections between existence of $\Bbbk$-rational points for Fano varieties defined over $\Bbbk$, a subfield of $\mathbb{C}$, and existence of Kähler-Einstein metrics on their geometric models. First, we show that geometric models of del Pezzo surfaces with at worst quotient singularities defined over $\Bbbk\subset\mathbb{C}$ admit (orbifold) Kähler--Einstein metrics if they do not have $\Bbbk$-rational points. Then we prove the same result for smooth Fano 3-folds with 8 exceptions. Consequently, we explicitly describe several families of pointless Fano 3-folds whose geometric models admit Kähler-Einstein metrics. In particular, we obtain new examples of prime Fano 3-folds of genus $12$ that admit Kähler--Einstein metrics. Our result can also be used to prove existence of rational points for certain Fano varieties, for example for any smooth Fano 3-fold over $\Bbbk\subset\mathbb{C}$ whose geometric model is strictly K-semistable.
title K-stability of pointless del Pezzo surfaces and Fano 3-folds
topic Algebraic Geometry
14J45, 32Q20
url https://arxiv.org/abs/2411.00767