A skew Specht perspective of RoCK blocks and cuspidal systems for KLR algebras in affine type A

Abstract

Cuspidal systems parameterize KLR algebra representations via root partitions $\pi$, where simple modules $L(\pi )$ arise as heads of proper standard modules. Working in affine type A with an arbitrary convex preorder, we construct explicit skew diagrams $\zeta (\pi )$ such that the skew Specht module $S^{\zeta (\pi )}$ has simple head $L(\pi )$ and a filtration by proper standard modules. A key ingredient in this construction is the development of `core-truncation' functors, which take module categories of level one RoCK blocks to the category of imaginary semicuspidal KLR modules. Every simple imaginary semicuspidal module arises in the image of these functors. This result stems from an in-depth study of the combinatorial interplay between cuspidal systems and RoCK cyclotomic KLR algebras, in which we characterize core blocks and RoCK blocks in arbitrary level via cuspidal tiling properties of multipartitions in these blocks.

arXiv commentv2 adds a new theorem, appearing as Theorem F in the introduction. Other minor edits. v3 is the final version, to appear in Representation Theory

References in corpus (7)

• A diagrammatic approach to categorification of quantum groups I
• Blocks of cyclotomic Hecke algebras and Khovanov-Lauda algebras
• Graded Specht modules
• Convex Bases of PBW type for Quantum Affine Algebras
• Universal Specht modules for cyclotomic Hecke algebras
• Mirkovic-Vilonen polytopes and Khovanov-Lauda-Rouquier algebras
• Core blocks for Hecke algebras of type B and sign sequences