English

Counting elliptic curves with prescribed entanglements

Number Theory 2025-12-02 v1

Abstract

We establish asymptotic lower bounds for the number of elliptic curves over Q\mathbb{Q} with prescribed entanglement of division fields, ordered by naive height. Such elliptic curves are obtained as 11-parameter families arising from certain genus 00 modular curves. We apply techniques from the geometry of numbers and sieve methods to prove that the number of elliptic curves with unexplained entanglements Q(E[2])Q(E[3])Q\mathbb{Q}(E[2]) \cap \mathbb{Q}(E[3]) \neq \mathbb{Q} and Q(E[2])Q(E[5])Q\mathbb{Q}(E[2]) \cap \mathbb{Q}(E[5]) \neq \mathbb{Q} and naive height X\leq X, grows as X1/9\gg X^{1/9} and X1/12\gg X^{1/12}, respectively.

Keywords

Cite

@article{arxiv.2511.11948,
  title  = {Counting elliptic curves with prescribed entanglements},
  author = {Zachary Couvillon and Anwesh Ray},
  journal= {arXiv preprint arXiv:2511.11948},
  year   = {2025}
}

Comments

15 pages, accepted for publication in Research in Number theory

R2 v1 2026-07-01T07:38:34.463Z