A new spin on Hurwitz theory and ELSV via theta characteristics

Giacchetto, Alessandro and Kramer, Reinier and Lewanski, Danilo (2021) A new spin on Hurwitz theory and ELSV via theta characteristics. MPIM Preprint Series 2021 (14).

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Abstract

We study spin Hurwitz numbers, which count ramified covers of the Riemann sphere with a sign coming from a theta characteristic. These numbers are known to be related to Gromov-Witten theory of Kähler surfaces and to representation theory of the Sergeev group, and are generated by BKP tau-functions. We use the latter interpretation to give polynomiality properties of these numbers and we derive a spectral curve which we conjecture computes spin Hurwitz numbers via a new type of topological recursion. We prove that this conjectural topological recursion is equivalent to an ELSV-type formula, expressing spin Hurwitz numbers in terms of the Chiodo class twisted by the 2-spin Witten class.

Item Type: MPIM Preprint
Subjects: 1 Discrete mathematics / algebra > 14-XX Algebraic geometry
Divisions: Research > Preprints
Depositing User: Andrea Kohlhuber
Date Deposited: 18 May 2021 09:59
Last Modified: 18 May 2021 11:04
URI: https://archive.mpim-bonn.mpg.de/id/eprint/4544

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