On Iwasawa theory of Rubin-Stark units and narrow class groups

TL;DR

This paper investigates the relationship between narrow class groups and Rubin-Stark units in totally real number fields, providing new insights into their Iwasawa-theoretic properties and characteristic ideals.

Contribution

It establishes a comparison between the characteristic ideals of narrow class groups and Rubin-Stark units in the context of Iwasawa theory for totally real fields.

Findings

Comparison of characteristic ideals for narrow class groups and Rubin-Stark units

Results on the structure of projective limits of units and class groups

Advances in understanding Iwasawa modules in totally real fields

Abstract

Let $K$ be a totally real number field of degree $r$. Let $K_{\infty}$ denote the cyclotomic $\mathbb{Z}_{2}$-extension of $K$ and let $L_{\infty}$ be a finite extension of $K_{\infty}$, abelian over $K$. The goal of this paper is to compare the characteristic ideal of the $\chi$-quotient of the projective limit of the narrow class groups to the $\chi$-quotient of the projective limit of the $r$-th exterior power of totally positive units modulo a subgroup of Rubin-Stark units, for some $\overline{\mathbb{Q}_{2}}$-irreducible characters $\chi$ of $\mathrm{Gal}(L_{\infty}/K_{\infty})$.