<i>k</i>-leaky double Hurwitz descendants

Abstract We define a new class of enumerative invariants called k -leaky double Hurwitz descendants, generalizing both descendant integrals of double ramification cycles and the k -leaky double Hurwitz numbers introduced in [CMR25]. These numbers are defined as intersection numbers of the logarithmic DR cycle against $\psi $ -classes and logarithmic classes coming from piecewise polynomials encoding fixed branch point conditions. We give a tropical graph sum formula for these new invariants, allowing us to show their piecewise polynomiality in any genus. Investigating the piecewise polynomial structure further (and restricting to genus zero for this purpose), we also show a wall-crossing formula. We also prove that in genus zero the invariants are always nonnegative and give a complete classification of the cases where they vanish.

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Publication Details

Journal
Forum of Mathematics Sigma
Published
2025-01-01
DOI
https://doi.org/10.1017/fms.2025.26
Primary Topic
Algebraic Geometry and Number Theory
Type
article
Field-Weighted Citation Impact
0.00

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article

k-leaky double Hurwitz descendants

Johannes Schmitt, Renzo Cavalieri, Hannah Markwig
Forum of Mathematics Sigma
Algebraic Geometry and Number Theory
article

k-leaky double Hurwitz descendants

Johannes Schmitt, Renzo Cavalieri, Hannah Markwig
article en

Abstract

Abstract We define a new class of enumerative invariants called k -leaky double Hurwitz descendants, generalizing both descendant integrals of double ramification cycles and the k -leaky double Hurwitz numbers introduced in [CMR25]. These numbers are defined as intersection numbers of the logarithmic DR cycle against $\psi $ -classes and logarithmic classes coming from piecewise polynomials encoding fixed branch point conditions. We give a tropical graph sum formula for these new invariants, allowing us to show their piecewise polynomiality in any genus. Investigating the piecewise polynomial structure further (and restricting to genus zero for this purpose), we also show a wall-crossing formula. We also prove that in genus zero the invariants are always nonnegative and give a complete classification of the cases where they vanish.

Forum of Mathematics SigmaVol. 13
University of Zurich (CH), University of Tübingen (DE), Colorado State University (US)
National Science Foundation, National Centres of Competence in Research SwissMAP, Deutsche Forschungsgemeinschaft, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Openalex Percentile: Top 90%
Algebraic Geometry and Number Theory
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<i>k</i>-leaky double Hurwitz descendants — Johannes Schmitt, Renzo Cavalieri, et al. · Forum of Mathematics Sigma (2025) | TGRS Research Map | TGRS