Schurian-finiteness of blocks of type $A$ Hecke algebras II

Abstract

For any algebra $A$ over an algebraically closed field $\mathbb{F}$, we say that an $A$-module $M$ is Schurian if ${\mathrm{End}}_A(M)\cong \mathbb{F}$. We say that $A$ is Schurian-finite if there are only finitely many isomorphism classes of Schurian $A$-modules, and Schurian-infinite otherwise. In this paper, we build on the work of Ariki and the second author to show that all blocks of type $A$ Hecke algebras of weight at least $2$ in quantum characteristic $e\ge 3$ are Schurian-infinite. This proves that if $e\ge 3$ then blocks of type $A$ Hecke algebras are Schurian-finite if and only if they are representation-finite.

This paper has now been combined with its prequel paper, arXiv:2112.11148. The results are subsumed by that paper, which should be considered the definitive version