Finite isoresidual covers in strata of $k$-differentials

Fuente: arXiv
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Main Authors: Chen, Dawei, Gendron, Quentin, Prado, Miguel, Tahar, Guillaume
Format: Preprint
Published: 2025
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author Chen, Dawei
Gendron, Quentin
Prado, Miguel
Tahar, Guillaume
author_facet Chen, Dawei
Gendron, Quentin
Prado, Miguel
Tahar, Guillaume
contents Consider the strata of primitive $k$-differentials on the Riemann sphere whose singularities, except for two, are poles of order divisible by $k$. The map that assigns to each $k$-differential the $k$-residues at these poles is a ramified cover of its image. Generalizing results known in the case of abelian differentials, we describe the ramification locus of this cover and provide a formula, involving the $k$-factorial function, for the cardinality of each fiber. We prove this formula using intersection calculations on the multi-scale compactification of the strata of $k$-differentials. In special cases, we also give alternative proofs using flat geometry. Finally, we present an application to cone spherical metrics with dihedral monodromy.
format Preprint
id arxiv_https___arxiv_org_abs_2510_01630
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Finite isoresidual covers in strata of $k$-differentials
Chen, Dawei
Gendron, Quentin
Prado, Miguel
Tahar, Guillaume
Algebraic Geometry
Combinatorics
Geometric Topology
Consider the strata of primitive $k$-differentials on the Riemann sphere whose singularities, except for two, are poles of order divisible by $k$. The map that assigns to each $k$-differential the $k$-residues at these poles is a ramified cover of its image. Generalizing results known in the case of abelian differentials, we describe the ramification locus of this cover and provide a formula, involving the $k$-factorial function, for the cardinality of each fiber. We prove this formula using intersection calculations on the multi-scale compactification of the strata of $k$-differentials. In special cases, we also give alternative proofs using flat geometry. Finally, we present an application to cone spherical metrics with dihedral monodromy.
title Finite isoresidual covers in strata of $k$-differentials
topic Algebraic Geometry
Combinatorics
Geometric Topology
url https://arxiv.org/abs/2510.01630