English

The Lang-Trotter conjecture on average for genus-$2$ curves with $S_3$ reduced automorphism group

Number Theory 2026-04-02 v1

Abstract

For an elliptic curve EE over Q\mathbb{Q} without complex multiplication, Lang and Trotter conjectured that the number of primes p<Xp <X at which EE has a supersingular reduction is asymptotically equal to cX/logXc\sqrt{X}/\log X, where c>0c>0 is a constant depending only on EE. While it remains an open question, an average estimation related to the Lang-Trotter conjecture was established by Fouvry and Murty. This result is called the Lang-Trotter conjecture on average. We extend the Lang-Trotter conjecture to curves of genus 22 and obtain a similar result to the Lang-Trotter conjecture on average for the family of curves Cλ:y2=x(x1)(xλ)(x(λ1)/λ)(x1/(1λ))C_{\lambda}:y^2=x(x-1)(x-{\lambda})(x-(\lambda-1)/{\lambda})(x-1/ (1-\lambda)). These curves are characterized as curves of genus 22 with reduced automorphism group containing symmetric group S3S_3.

Keywords

Cite

@article{arxiv.2604.00822,
  title  = {The Lang-Trotter conjecture on average for genus-$2$ curves with $S_3$ reduced automorphism group},
  author = {Chihiro Ando and Shushi Harashita},
  journal= {arXiv preprint arXiv:2604.00822},
  year   = {2026}
}

Comments

49 pages