English

CM elliptic curves and vertically entangled 2-adic groups

Number Theory 2023-01-05 v1

Abstract

Consider the elliptic curve EE given by the Weierstrass equation y2=x311x14y^2 = x^3 - 11x - 14, which has complex multiplication by the order of conductor 22 inside Z[i]\mathbb{Z}[i]. It was recently observed in a paper of Daniels and Lozano-Robledo that, for each n2n \geq 2, Q(μ2n+1)Q(E[2n])\mathbb{Q}(\mu_{2^{n+1}}) \subseteq \mathbb{Q}(E[2^n]). In this note, we prove that this (a priori surprising) ``tower of vertical entanglements'' is actually more a feature than a bug: it holds for any elliptic curve EE over Q\mathbb{Q} with complex multiplication by any order of even discriminant.

Keywords

Cite

@article{arxiv.2301.01680,
  title  = {CM elliptic curves and vertically entangled 2-adic groups},
  author = {Nathan Jones},
  journal= {arXiv preprint arXiv:2301.01680},
  year   = {2023}
}
R2 v1 2026-06-28T08:02:42.512Z