%0 Journal Article %T Analytic R-groups of affine Hecke algebras %+ Institut de mathématiques de Luminy (IML) %+ Korteweg-de Vries Institute for Mathematics %A Delorme, Patrick %A Opdam, Eric %Z Some improvements in the presentation were made, and an example has been added showing the nontriviality of the cohomology class of the 2-cocycle $\gamma_\Delta$ (as opposed to $\gamma$ itself) for Hecke algebras of type D %< avec comité de lecture %@ 0075-4102 %J Journal für die reine und angewandte Mathematik %I Walter de Gruyter %V 2011 %N 658 %P 133-172 %8 2011-01 %D 2011 %Z 0909.1227 %R 10.1515/crelle.2011.064 %Z 20C08, 22D25, 22E35, 43A40 %Z Mathematics [math]/Representation Theory [math.RT]Journal articles %X We define analytic $R$-groups for affine Hecke algebras, and prove the analog of the Knapp-Stein Dimension Theorem. As a corollary we prove that the commutant algebra of a unitary principal series representation is isomorphic to the complex group algebra of the $R$-group, twisted by a certain 2-cocycle $\gamma$. For classical Hecke algebras we prove that $\gamma$ is always trivial. %G English %L hal-01273294 %U https://hal.science/hal-01273294 %~ CNRS %~ UNIV-AMU %~ IML %~ I2M %~ ANR