Codimension two cycles in Iwasawa theory and tensor product of Hida families

TL;DR

This paper advances higher codimension Iwasawa theory by relating tensor products of Hida families and their associated multi-variable p-adic L-functions to codimension two cycles and pseudo-null modules.

Contribution

It establishes new relationships between multi-variable p-adic L-functions and codimension two cycles in deformation rings for tensor products of Hida families.

Findings

Relations between p-adic L-functions and codimension two cycles.

Use of pseudo-null modules to understand Iwasawa-theoretic structures.

Extension of higher codimension Iwasawa theory results.

Abstract

The purpose of this paper is to build on results in {\it{higher codimension Iwasawa theory}}. The setting of our results involves Galois representations arising as cyclotomic twist deformations associated to (i) the tensor product of two cuspidal Hida families $F$ and $G$, and (ii) the tensor product of three cuspidal Hida families $F$, $G$ and $H$. On the analytic side, we consider (i) a pair of $3$-variable Rankin-Selberg $p$-adic $L$-functions constructed by Hida and (ii) a balanced $4$-variable $p$-adic $L$-function (due to Hsieh and Yamana) and an unbalanced $4$-variable $p$-adic $L$-function (whose existence is currently conjectural). In each of these setups, when the two $p$-adic $L$-functions generate a height two ideal in the corresponding deformation ring, we use codimension two cycles of that ring to relate them to a pair of pseudo-null modules.