Representations of rank two affine Hecke algebras

Abstract

This paper classifies and constructs explicitly all the irreducible representations of affine Hecke algebras of rank two root systems. The methods used to obtain this classification are primarily combinatorial and are, for the most part, an application of the methods used in a recent preprint of Ram. A special effort has been made special effort to describe how the classification here relates to the classifications by Langlands parameters (coming from p-adic group theory) and by indexing triples (coming from a q-analogue of the Springer correspondence). The examples here illustrate and clarify results of Ram, Kazhdan-Lusztig, Chriss-Ginzburg, Barbasch-Moy, Evens, Kriloff, and Heckman-Opdam. Much of the power of the combinatorial methods which are now available is evident from the calculations in this paper. One hopes that eventually there will be a combinatorial construction of all irreducible representations of all affine Hecke algebras. Such a construction may depend heavily on the rank two cases. This idea is analogous to the way that the rank two cases are the basic building blocks in the presentations of Coxeter groups by ``braid'' relations and the presentations of Kac-Moody Lie algebras (and quantum groups) by Serre relations.