Le lemme fondamental pour l'endoscopie tordue: le cas o{\`u} le groupe endoscopique non ramifi{\'e} est un tore

Abstract

We prove the fundamental lemma for twisted endoscopy, for the unit elements of the spherical Hecke algebras, in the case of a non ramified elliptic endo- scopic datum whose underlying group is a torus. This implies that the fundamental lemma for twisted endoscopy is now proved, for all elements in the spherical Hecke algebras, in characteristic zero and any residue characteristic.