On the monodromy map for the logarithmic differential systems

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Main Authors: Aprodu, Marian, Biswas, Indranil, Dumitrescu, Sorin, Heller, Sebastian
Format: Preprint
Published: 2022
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author Aprodu, Marian
Biswas, Indranil
Dumitrescu, Sorin
Heller, Sebastian
author_facet Aprodu, Marian
Biswas, Indranil
Dumitrescu, Sorin
Heller, Sebastian
contents We study the monodromy map for logarithmic $\mathfrak g$-differential systems over an oriented surface $S_0$ of genus $g$, with $\mathfrak g$ being the Lie algebra of a complex reductive affine algebraic group $G$. These logarithmic $\mathfrak g$-differential systems are triples of the form $(X, D,Φ)$, where $(X, D) \in {\mathcal T}_{g,d}$ is an element of the Teichmüller space of complex structures on $S_0$ with $d \geq 1$ ordered marked points $D\subset S_0= X$ and $Φ$ is a logarithmic connection on the trivial holomorphic principal $G$-bundle $X \times G$ over $X$ whose polar part is contained in the divisor $D$. We prove that the monodromy map from the space of logarithmic $\mathfrak g$-differential systems to the character variety of $G$-representations of the fundamental group of $S_0\setminus D$ is an immersion at the generic point, in the following two cases: A) $g \geq 2$, $d \geq 1$, and $\dim_{\mathbb C}G \geq d+2$; B) $g=1$ and $\dim_{\mathbb C}G \geq d$. The above monodromy map is nowhere an immersion in the following two cases: 1) $g=0$ and $d \geq 4$; 2) $g\geq 1$ and $\dim_{\mathbb C}G < \frac{d+3g-3}{g}$. This extends to the logarithmic case the main results in \cite{CDHL}, \cite{BD} dealing with nonsingular holomorphic $\mathfrak g$-differential systems (which corresponds to the case of $d\,=\,0$).
format Preprint
id arxiv_https___arxiv_org_abs_2201_04095
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle On the monodromy map for the logarithmic differential systems
Aprodu, Marian
Biswas, Indranil
Dumitrescu, Sorin
Heller, Sebastian
Algebraic Geometry
Complex Variables
We study the monodromy map for logarithmic $\mathfrak g$-differential systems over an oriented surface $S_0$ of genus $g$, with $\mathfrak g$ being the Lie algebra of a complex reductive affine algebraic group $G$. These logarithmic $\mathfrak g$-differential systems are triples of the form $(X, D,Φ)$, where $(X, D) \in {\mathcal T}_{g,d}$ is an element of the Teichmüller space of complex structures on $S_0$ with $d \geq 1$ ordered marked points $D\subset S_0= X$ and $Φ$ is a logarithmic connection on the trivial holomorphic principal $G$-bundle $X \times G$ over $X$ whose polar part is contained in the divisor $D$. We prove that the monodromy map from the space of logarithmic $\mathfrak g$-differential systems to the character variety of $G$-representations of the fundamental group of $S_0\setminus D$ is an immersion at the generic point, in the following two cases: A) $g \geq 2$, $d \geq 1$, and $\dim_{\mathbb C}G \geq d+2$; B) $g=1$ and $\dim_{\mathbb C}G \geq d$. The above monodromy map is nowhere an immersion in the following two cases: 1) $g=0$ and $d \geq 4$; 2) $g\geq 1$ and $\dim_{\mathbb C}G < \frac{d+3g-3}{g}$. This extends to the logarithmic case the main results in \cite{CDHL}, \cite{BD} dealing with nonsingular holomorphic $\mathfrak g$-differential systems (which corresponds to the case of $d\,=\,0$).
title On the monodromy map for the logarithmic differential systems
topic Algebraic Geometry
Complex Variables
url https://arxiv.org/abs/2201.04095