A Note on the Spectral Transfer Morphisms for Affine Hecke Algebras

E. Opdam introduced the tool of spectral transfer morphism (STM) of affine Hecke algebras to study the formal degrees of unipotent discrete series representations. He established a uniqueness property of STM for the affine Hecke algebras associated of unipotent discrete series representations. Based on this result, Opdam gave an explanation for Lusztig's arithmetic/geometric correspondence (in Lusztig's classification of unipotent representations of $p$-adic adjoint simple groups) in terms of harmonic analysis, and partitioned the unipotent discrete series representations into $L$-packets based on the Lusztig-Langlands parameters. The present paper provides some omitted details for the argument of the uniqueness property of STM. In the last section, we prove that three finite morphisms of algebraic tori are spectral transfer morphisms, and hence complete the proof of the uniqueness property.Comment: title changed; irrelevant materials delete

Supercuspidal unipotent representations: L-packets and formal degrees

Let K be a non-archimedean local field and let G be a connected reductive K-group which splits over an unramified extension of K. We investigate supercuspidal unipotent representations of the group G(K). We establish a bijection between the set of irreducible G(K)-representations of this kind and the set of cuspidal enhanced L-parameters for G(K), which are trivial on the inertia subgroup of the Weil group of K. The bijection is characterized by a few simple equivariance properties and a comparison of formal degrees of representations with adjoint $\gamma$-factors of L-parameters. This can be regarded as a local Langlands correspondence for all supercuspidal unipotent representations. We count the ensueing L-packets, in terms of data from the affine Dynkin diagram of G. Finally, we prove that our bijection satisfies the conjecture of Hiraga, Ichino and Ikeda about the formal degrees of the representations.Comment: Version 2: minor corrections and additions, mainly in section 1