English

Root numbers of 5-adic curves of genus two having maximal ramification

Number Theory 2021-10-06 v3

Abstract

The formulas for local root numbers of abelian varieties of dimension one are known. In this paper we treat the simplest unknown case in dimension two by considering a curve of genus 2 defined over a 55-adic field such that the inertia acts on the first \ell-adic cohomology group through the largest possible finite quotient, isomorphic to C5C8C_5\rtimes C_8. We give a few criteria to identify such curves and prove a formula for their local root numbers in terms of invariants associated to a Weierstrass equation.

Keywords

Cite

@article{arxiv.2102.07745,
  title  = {Root numbers of 5-adic curves of genus two having maximal ramification},
  author = {Lukas Melninkas},
  journal= {arXiv preprint arXiv:2102.07745},
  year   = {2021}
}

Comments

22 pages; major revision: changed the title, deleted the part on elliptic curves (to appear in another submission), changed the formulation of the main result, shortened Section 1, corrected 1.8, merged and shortened Sections 2 and 3, the discussion on discriminants and conductors was rewritten and is now contained in 3.12, the four examples in section 7 were replaced by a new one in 5.9