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Coherent systems and Brill-Noether theory

Steven Bradlow·Oscar Garcia-Prada·Vicente Muñoz·Peter Newstead
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Abstract

Let $C$ be a curve of genus $g\geq 2$. A coherent system on $C$ consists of a pair $(E,V)$ where $E$ is an algebraic vector bundle of rank $n$ and degree $d$ and $V$ is a subspace of dimension $k$ of sections of $E$. The stability of the coherent systems depend on a parameter $τ$. We study the variation of the moduli space of coherent systems when we move the parameter. As an application, we analyse the cases $k=1,2,3$ and $n=2$ explicitly. For small values of $τ$, the moduli space of coherent systems is related to the Brill-Noether loci, the subspaces of the moduli space of stable bundles consisting of those bundles with a prescribed number of sections. The study of coherent systems is applied to find the dimension, irreducibility, and in some cases, the Picard group, of the Brill-Noether loci with $k\leq 3$.

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Steven Bradlow, Oscar Garcia-Prada, Vicente Muñoz, Peter Newstead. 2002-05-30. Coherent systems and Brill-Noether theory. https://arxiv.org/abs/math/0205317

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