. R T ] 4 M ay 2 01 7 ARTHUR PACKETS AND ADAMS - BARBASCH - VOGAN PACKETS FOR p - ADIC GROUPS , 1 : BACKGROUND AND CONJECTURES

This paper begins the project of adapting the 1992 book by Adams, Barbasch and Vogan on the Langlands classification of admissible representations of real groups, to padic groups, continuing in the direction charted by Vogan in his 1993 paper on the Langlands correspondence. This paper presents three theorems in that direction. The first theorem shows how Lusztig’s work on perverse sheaves arising from graded Lie algebras may be brought to bear on the problem; the second theorem proves that Arthur parameters determine strongly regular conormal vectors to a parameter space of certain Langlands parameters; the third theorem shows how to replace the microlocalisation functor as it appears in the work of Adams, Barbasch and Vogan with a functor built from Deligne’s vanishing cycles functor. The paper concludes with three conjectures, the first of which is the prediction that Arthur packets are Adams-Barbasch-Vogan packets for p-adic groups. This paper is the first in a series.