Rank distribution in cubic twist families of elliptic curves
Acta Arithmetica
MSC: Primary 11G05; Secondary 11R45, 11R34
DOI: 10.4064/aa240824-28-11
Published online: 22 May 2025
Abstract
Let $a$ be an integer which is not of the form $n^2$ or $-3 n^2$ for $n\in \mathbb {Z}$. Let $E_a$ be the elliptic curve with rational $3$-isogeny defined by $E_a:y^2=x^3+a$, and $K:=\mathbb {Q}(\mu _3)$. Assume that the $3$-Selmer group of $E_a$ over $K$ vanishes. It is shown that there is an explicit infinite set of cubefree integers $m$ such that the $3$-Selmer groups over $K$ of $E_{m^2 a}$ and $E_{m^4 a}$ both vanish. In particular, the ranks of these cubic twists are $0$ over $K$. Our results are proven by studying stability properties of $3$-Selmer groups in cyclic cubic extensions of $K$, via local and global Galois cohomological techniques.
