Variation of Iwasawa Invariants for Ordinary Representations

Abstract

Let $K$ be a number field and $p$ be an odd prime. Greenberg introduced a natural topology on the space of all ${\mathbb{Z}}_p$-extensions of $K$ and established several boundedness results for the classical Iwasawa invariants. We extend this framework to compare the Iwasawa invariants of Selmer groups attached to an ordinary $p$-adic representation across ${\mathbb{Z}}_p$-extensions lying in a Greenberg neighbourhood in the sense of Greenberg. We also establish analogous results for the fine Selmer groups. Finally, in a neighbourhood of the cyclotomic ${\mathbb{Z}}_p$-extension, we provide evidence for the expected connection between the characteristic ideal of the Selmer group and the conjectural $p$-adic $L$-function introduced by Disegni.

14 pages