English

The moduli space of cyclic covers in positive characteristic

Algebraic Geometry 2024-04-12 v3 Number Theory

Abstract

We study the pp-rank stratification of the moduli space ASW(d1,d2,,dn)\mathcal{ASW}_{(d_1,d_2,\ldots,d_n)}, which represents Z/pn\mathbb{Z}/p^n-covers in characteristic p>0p>0 whose Z/pi\mathbb{Z}/p^i-subcovers have conductor did_i. In particular, we identify the irreducible components of the moduli space and determine their dimensions. To achieve this, we analyze the ramification data of the represented curves and use it to classify all the irreducible components of the space. In addition, we provide a comprehensive list of pairs (p,(d1,d2,,dn))(p,(d_1,d_2,\ldots,d_n)) for which ASW(d1,d2,,dn)\mathcal{ASW}_{(d_1,d_2,\ldots,d_n)} in characteristic pp is irreducible. Finally, we investigate the geometry of ASW(d1,d2,,dn)\mathcal{ASW}_{(d_1,d_2,\ldots,d_n)} by studying the deformations of cyclic covers which vary the pp-rank and the number of branch points.

Keywords

Cite

@article{arxiv.2306.14711,
  title  = {The moduli space of cyclic covers in positive characteristic},
  author = {Huy Dang and Matthias Hippold},
  journal= {arXiv preprint arXiv:2306.14711},
  year   = {2024}
}

Comments

Fix a mistake in Theorem 4.16, remove Proposition 4.14, and make some minor changes