The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $

Let $ X $ be a compact Riemann surface of genus $ g\geq 2 $. The moduli space $ \mathcal{M}(r, d) $ of rank $ r $ and degree $ d $ semi-stable Higgs bundles over $ X $ admitted a stratification, called Shatz stratification, which was defined by the Harder-Narasimhan type of the Higgs bundles. There...

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Main Author: Álvaro Antón-Sancho
Format: Article
Language:English
Published: AIMS Press 2025-02-01
Series:AIMS Mathematics
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Online Access:https://www.aimspress.com/article/doi/10.3934/math.2025159
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author Álvaro Antón-Sancho
author_facet Álvaro Antón-Sancho
author_sort Álvaro Antón-Sancho
collection DOAJ
description Let $ X $ be a compact Riemann surface of genus $ g\geq 2 $. The moduli space $ \mathcal{M}(r, d) $ of rank $ r $ and degree $ d $ semi-stable Higgs bundles over $ X $ admitted a stratification, called Shatz stratification, which was defined by the Harder-Narasimhan type of the Higgs bundles. There was also a $ \mathbb{C}^* $-action on $ \mathcal{M}(r, d) $ given by the product on the Higgs field, which provided the Białynicki-Birula stratification by considering the Hodge limit bundles $ \lim_{z\to 0}(E, z\cdot\varphi) $. In this paper, these limit bundles were computed for all possible Harder-Narasimhan types when the rank of the Higgs bundles was $ r = 5 $, explicit vector forms were provided for the Hodge limit bundles, and necessary and sufficient conditions were given for them to be stable. In addition, it was proved that, in rank $ 5 $, the Shatz strata traversed the Białynicki-Birula strata. Specifically, it was checked that there existed different semi-stable rank $ 5 $ Higgs bundles with the same Harder-Narasimhan type such that their associated Hodge limit bundles were not S-equivalent, and explicit constructions of those Higgs bundles were also provided.
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spelling doaj-art-569d16165b9d4ff9bde0111deea634b12025-08-20T02:26:19ZengAIMS PressAIMS Mathematics2473-69882025-02-011023428345610.3934/math.2025159The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $Álvaro Antón-Sancho0Department of Mathematics and Experimental Science, Fray Luis de León University College of Education, C/Tirso de Molina, 44, 47010 Valladolid, SpainLet $ X $ be a compact Riemann surface of genus $ g\geq 2 $. The moduli space $ \mathcal{M}(r, d) $ of rank $ r $ and degree $ d $ semi-stable Higgs bundles over $ X $ admitted a stratification, called Shatz stratification, which was defined by the Harder-Narasimhan type of the Higgs bundles. There was also a $ \mathbb{C}^* $-action on $ \mathcal{M}(r, d) $ given by the product on the Higgs field, which provided the Białynicki-Birula stratification by considering the Hodge limit bundles $ \lim_{z\to 0}(E, z\cdot\varphi) $. In this paper, these limit bundles were computed for all possible Harder-Narasimhan types when the rank of the Higgs bundles was $ r = 5 $, explicit vector forms were provided for the Hodge limit bundles, and necessary and sufficient conditions were given for them to be stable. In addition, it was proved that, in rank $ 5 $, the Shatz strata traversed the Białynicki-Birula strata. Specifically, it was checked that there existed different semi-stable rank $ 5 $ Higgs bundles with the same Harder-Narasimhan type such that their associated Hodge limit bundles were not S-equivalent, and explicit constructions of those Higgs bundles were also provided.https://www.aimspress.com/article/doi/10.3934/math.2025159higgs bundlestratificationactionharder-narasimhan typesemi-stablemoduli space
spellingShingle Álvaro Antón-Sancho
The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
AIMS Mathematics
higgs bundle
stratification
action
harder-narasimhan type
semi-stable
moduli space
title The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
title_full The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
title_fullStr The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
title_full_unstemmed The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
title_short The $ \mathbb{C}^* $-action and stratifications of the moduli space of semi-stable Higgs bundles of rank $ 5 $
title_sort mathbb c action and stratifications of the moduli space of semi stable higgs bundles of rank 5
topic higgs bundle
stratification
action
harder-narasimhan type
semi-stable
moduli space
url https://www.aimspress.com/article/doi/10.3934/math.2025159
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