English

Large Tate--Shafarevich orders from good $abc$ triples

Number Theory 2021-11-16 v1

Abstract

Record values are determined for the order \Sha|\Sha| of the Tate--Shafarevich group of an elliptic curve EE, computed analytically by the Birch--Swinnerton-Dyer conjecture, and for the Goldfeld--Szpiro ratio G=\Sha/NG=|\Sha|/\sqrt{N}, where NN is the conductor of EE. The curves have rank zero and are isogenous to quadratic twists of Frey curves constructed from coprime positive integers (a,b,c)(a,b,c) with a+b=ca+b=c and c>r1.4c>r^{1.4}, where the radical rr is the product of the primes dividing abcabc. Curves with \Sha>2500002|\Sha|>250000^2 and G>12G>12 are found in 20 isogeny classes. Three curves have G>150G>150. The largest value of \Sha|\Sha| is 19378322>3.755×10121937832^2>3.755\times10^{12}. This is more than 3.5 times the previous record, which had been computed at a cost about 600 times greater than that for the new record. The primes 25913, 27457, 36929 and 49253 are identified as divisors of \Sha|\Sha| values.

Cite

@article{arxiv.2111.07794,
  title  = {Large Tate--Shafarevich orders from good $abc$ triples},
  author = {David Broadhurst},
  journal= {arXiv preprint arXiv:2111.07794},
  year   = {2021}
}

Comments

17 pages

R2 v1 2026-06-24T07:38:52.982Z