Higgs fields, non-abelian Cauchy kernels and the Goldman symplectic structure

Fuente: arXiv
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Autori principali: Bertola, Marco, Norton, Chaya, Ruzza, Giulio
Natura: Preprint
Pubblicazione: 2021
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author Bertola, Marco
Norton, Chaya
Ruzza, Giulio
author_facet Bertola, Marco
Norton, Chaya
Ruzza, Giulio
contents We consider the moduli space of vector bundles of rank $n$ and degree $ng$ over a fixed Riemann surface of genus $g\geq 2$. We use the explicit parametrization in terms of the Tyurin data. In the moduli space there is a "non-abelian" Theta divisor, consisting of bundles with $h^1\geq 1$. On the complement of this divisor we construct a non-abelian Cauchy kernel explicitly in terms of the Tyurin data. With the additional datum of a non-special divisor, we can construct a reference flat holomorphic connection which is also dependent holomorphically on the moduli of the bundle. This allows us to identify the bundle of Higgs fields, i.e. the cotangent bundle of the moduli space, with the affine bundle of holomorphic connections and provide a monodromy map into the ${\rm GL}_n$ character variety. We show that the Goldman symplectic structure on the character variety pulls back along this map to the complex canonical symplectic structure on the cotangent bundle and hence also on the space of affine connections. The pull-back of the Liouville one-form to the affine bundle of connections is then shown to be a logarithmic form with poles along the non-abelian theta divisor and residue given by $h^1$.
format Preprint
id arxiv_https___arxiv_org_abs_2102_09520
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Higgs fields, non-abelian Cauchy kernels and the Goldman symplectic structure
Bertola, Marco
Norton, Chaya
Ruzza, Giulio
Algebraic Geometry
Mathematical Physics
Symplectic Geometry
We consider the moduli space of vector bundles of rank $n$ and degree $ng$ over a fixed Riemann surface of genus $g\geq 2$. We use the explicit parametrization in terms of the Tyurin data. In the moduli space there is a "non-abelian" Theta divisor, consisting of bundles with $h^1\geq 1$. On the complement of this divisor we construct a non-abelian Cauchy kernel explicitly in terms of the Tyurin data. With the additional datum of a non-special divisor, we can construct a reference flat holomorphic connection which is also dependent holomorphically on the moduli of the bundle. This allows us to identify the bundle of Higgs fields, i.e. the cotangent bundle of the moduli space, with the affine bundle of holomorphic connections and provide a monodromy map into the ${\rm GL}_n$ character variety. We show that the Goldman symplectic structure on the character variety pulls back along this map to the complex canonical symplectic structure on the cotangent bundle and hence also on the space of affine connections. The pull-back of the Liouville one-form to the affine bundle of connections is then shown to be a logarithmic form with poles along the non-abelian theta divisor and residue given by $h^1$.
title Higgs fields, non-abelian Cauchy kernels and the Goldman symplectic structure
topic Algebraic Geometry
Mathematical Physics
Symplectic Geometry
url https://arxiv.org/abs/2102.09520