On the cyclotomic Iwasawa invariants of elliptic curves of rank one
Foivos Chnaras
TL;DR
The paper develops explicit numerical criteria to determine when the Iwasawa invariants $\mu_p$ and $\lambda_p$ of a rank-one elliptic curve over $\mathbb{Q}$ attain their minimal possible value in the cyclotomic $\mathbb{Z}_p$-extension, distinguishing good ordinary and supersingular primes. It introduces a Fermat-quotient based test via a specific multiple $Q$ of a Mordell–Weil generator, linking $a(Q)^{p-1}$ modulo $p^2$ (and $d(Q)$ modulo $p^2$ in the supersingular case) to $\mu_p$ and $\lambda_p$ through the $p$-adic regulator and $p$-adic BSD. The framework relies on p-adic regulator constructions (Mazur–Tate sigma function, Dieudonné module, signed $p$-adic $L$-functions) and the main conjectures for ordinary and supersingular cases, providing concrete, computable criteria and illustrating them with explicit examples. Additionally, the work discusses model-minimality issues, Tamagawa-scale corrections, and a Tamagawa-theorem that clarifies how minimal models affect local indices, with practical implications for computing the $p$-adic height and Iwasawa data. Overall, the results offer a practical, theory-driven approach to assessing when Rank $1$ curves exhibit minimal Iwasawa invariants in the cyclotomic tower, supported by computational evidence and explicit algorithms.
Abstract
Fix an elliptic curve $E$ over $\mathbb Q$ of rank $1$. In this paper, we develop an explicit numerical criterion, comparable to Gold's criterion, that determines whether the Iwasawa invariants of the elliptic curve at a good (ordinary or supersingular) prime attain their smallest possible value, i.e. whether $μ_p^\pm(E) +λ^\pm_p(E)=1$ in the supersingular case or $μ_p(E) + λ_p(E)=1$ in the ordinary case.
