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Let G be an affine reductive algebraic group over an algebraically closed field k. We determine the Picard group of the moduli stacks of principal G-bundles on any smooth projective curve over k.

Algebraic Geometry · Mathematics 2023-10-04 Indranil Biswas , Norbert Hoffmann

Our interest in this paper is a generalization of the additive Deligne-Simpson problem which is originally defined for Fuchsian differential equations on the Riemann sphere. We shall extend this problem to differential equations having an…

Classical Analysis and ODEs · Mathematics 2017-04-05 Kazuki Hiroe

It was suggested on several occasions by Deligne, Drinfeld and Kontsevich that all the moduli spaces arising in the classical problems of deformation theory should be extended to natural "derived" moduli spaces which are always smooth in an…

alg-geom · Mathematics 2007-05-23 M. Kapranov

Let $\pi\colon P\to M$ be a principal bundle and $p$ an invariant polynomial of degree r on the Lie algebra of the structure group. The theory of Chern-Simons differential characters is exploited to define an homology map $\chi^{k} :…

Differential Geometry · Mathematics 2018-05-21 Marco Castrillón López , Roberto Ferreiro Pérez

In this survey article we describe moduli spaces of simple, stable, and semistable sheaves on K3 surfaces, following the work of Mukai, O'Grady, Huybrechts, Yoshioka, and others. We also describe some recent developments, including…

Algebraic Geometry · Mathematics 2021-12-28 Justin Sawon

Let X be a smooth projective variety over C. We find the natural notion of semistable orthogonal bundle and construct the moduli space, which we compactify by considering also orthogonal sheaves, i.e. pairs (E,\phi), where E is a torsion…

Algebraic Geometry · Mathematics 2007-05-23 Tomas L. Gomez , Ignacio Sols

In this paper, we prove that the moduli space $\overline{M}_{X}(\nu)$ of $H$-Gieseker semistable sheaves on a smooth cubic threefold $X$ with Chern character $\nu=(4,-H,-\frac{5}{6}H^{2},\frac{1}{6}H^{3})$ is non-empty, smooth and…

Algebraic Geometry · Mathematics 2024-09-24 Shihao Ma , Song Yang

The modular curves serve as excellent objects for testing conjectures in arithmetic geometry. They possess a natural geometric definition in contrast with rather nontrivial structure. On the other hand, they are well-studied from the…

Algebraic Geometry · Mathematics 2025-01-14 A. Levin , N. Sakharova

We consider stable and semistable principal bundles over a smooth projective real algebraic curve, equipped with a real or pseudo-real structure in the sense of Atiyah. After fixing suitable topological invariants, one can build a suitable…

Algebraic Geometry · Mathematics 2015-09-29 Indranil Biswas , Oscar Garcia-Prada , Jacques Hurtubise

Let $G$ be a reductive algebraic group. A toric principal $G$-bundle is a principal $G$-bundle over a toric variety together with a torus action commuting with the $G$-action. Extending the Klyachko classification of toric vector bundles,…

Algebraic Geometry · Mathematics 2026-04-13 Shaoyu Huang , Kiumars Kaveh

We show that the moduli space of semistable G-bundles on an elliptic curve for a reductive group G is isomorphic to a power of the elliptic curve modulo a certain Weyl group which depend on the topological type of the bundle. This…

Algebraic Geometry · Mathematics 2020-02-07 Dragoş Frăţilă

Let $G$ be an algebraic group and $\Gamma$ a finite subgroup of automorphisms of $G$. Fix also a possibly ramified $\Gamma$-covering $\widetilde{X} \to X$. In this setting one may define the notion of $(\Gamma,G)$-bundles over…

Algebraic Geometry · Mathematics 2021-09-21 Chiara Damiolini

We show how to attach to any rigid analytic variety $V$ over a perfectoid space $P$ a rigid analytic motive over the Fargues-Fontaine curve $\mathcal{X}(P)$ functorially in $V$ and $P$. We combine this construction with the overconvergent…

Algebraic Geometry · Mathematics 2023-10-11 Arthur-César Le Bras , Alberto Vezzani

This note is but a research announcement, summarizing and explaining results proven and detailed in forthcoming papers. When one studies families of objects over curves, and the objects are parametrized by a Deligne-Mumford stack M, then…

Algebraic Geometry · Mathematics 2007-05-23 Dan Abramovich , Angelo Vistoli

Consider a Kleinian singularity $ \mathbb{C}^2/\Gamma $, where $ \Gamma $ is a finite subgroup of $ SL_2(\mathbb{C}) $. In this paper, we construct moduli spaces of framed sheaves on a projective Deligne-Mumford stack compactifying the…

Algebraic Geometry · Mathematics 2024-03-13 Søren Gammelgaard

Families of stable curves of genus $\gamma$ over a smooth curve $C$ correspond to morphisms from $C$ to the moduli stack of stable curves $\bar{\cal M}_\gamma$. It is natural to compactify the corresponding moduli problem using stable maps…

Algebraic Geometry · Mathematics 2007-05-23 Dan Abramovich , Angelo Vistoli

In this article, we derive estimates of Teichm\"uller modular forms, and associated invariants. Let $\mathcal{M}_{g}$ denote the moduli space of compact hyperbolic Riemann surfaces of genus $g\geq 2$, and let $\overline{M}_{g}$ be the…

Complex Variables · Mathematics 2024-12-19 Anilatmaja Aryasomayajula , Debasish Sadhukhan

In math.RT/0302174 we developed a framework to study representations of groups of the form $G((t))$, where $G$ is an algebraic group over a local field $K$. The main feature of this theory is that natural representations of groups of this…

Representation Theory · Mathematics 2007-05-23 Dennis Gaitsgory , David Kazhdan

In this paper, the first of a series of three, we classify holomorphic principal G-bundles over an elliptic curve, where G is a reductive group. We also study the local and global properties of the moduli space of semistable G-bundles. We…

Algebraic Geometry · Mathematics 2007-05-23 Robert Friedman , John W. Morgan

Let ${\cal S}{\cal U}(r, L_0)$ denote the moduli space of semi stable vector bundles of rank $r$ and fixed determinant $L_0$ of degree $d$ on a smooth curve $C$ of genus $g \geq 3$. In this paper we describe the group of automorphisms of $…

alg-geom · Mathematics 2008-02-03 Alexis Kouvidakis , Tony Pantev