English

Conductor-discriminant inequality for hyperelliptic curves in odd residue characteristic

Algebraic Geometry 2024-08-23 v4 Number Theory

Abstract

We prove an inequality between the conductor and the discriminant for all hyperelliptic curves defined over discretely valued fields KK with perfect residue field of characteristic not 2. Specifically, if such a curve is given by y2=f(x)y^2 = f(x) with f(x)OK[x]f(x) \in \mathcal{O}_K[x], and if XX is its minimal regular model over OK\mathcal{O}_K, then the negative of the Artin conductor of XX (and thus also the number of irreducible components of the special fiber of XX) is bounded above by the valuation of disc(f)(f). There are no restrictions on genus of the curve or on the ramification of the splitting field of ff. This generalizes earlier work of Ogg, Saito, Liu, and the second author.

Keywords

Cite

@article{arxiv.1910.02589,
  title  = {Conductor-discriminant inequality for hyperelliptic curves in odd residue characteristic},
  author = {Andrew Obus and Padmavathi Srinivasan},
  journal= {arXiv preprint arXiv:1910.02589},
  year   = {2024}
}

Comments

Final version, to appear in IMRN. Main argument drastically shortened per referee's suggestions. Now 13 pp