English

Counting points on a family of degree one del Pezzo surfaces

Number Theory 2026-04-22 v2

Abstract

We study rational points on the elliptic surface given by the equation: y2=x3+AxQ(u,v)2+BQ(u,v)3,y^2 = x^3 + AxQ(u,v)^2 + BQ(u,v)^3, where A,BZA,B\in \mathbb{Z} satisfy that 4A327B204A^3-27B^2\neq 0 and Q(u,v)Q(u,v) is a positive-definite quadratic form. We prove asymptotics for a special subset of the rational points, specifically those that are integral with respect to the singularity. This method utilizes Mordell's parameterization of integral points on quadratic twists on elliptic curves, which is based on a syzygy for invariants of binary quartic forms. Let F(A,B)F(A,B) denote the set of binary quartic forms with invariants 4A-4A and 4B-4B under the action of SL2(Z)\textrm{SL}_2(\mathbb{Z}). We reduce the point-counting problem to the question of determining an asymptotic formula for the correlation sums of representation numbers of binary quadratic and binary quartic forms, where the quartic forms range in F(A,B)F(A,B). These sums are then treated using a connection to modular forms.

Keywords

Cite

@article{arxiv.2508.09391,
  title  = {Counting points on a family of degree one del Pezzo surfaces},
  author = {Katharine Woo},
  journal= {arXiv preprint arXiv:2508.09391},
  year   = {2026}
}

Comments

Revised version; appendix on base change and sums of hecke eigenvalues along polynomials separated to a new paper