The Bernstein twisted extended-quotient conjecture

Let FF) be a non-archimedean local field and GG a connected reductive algebraic group over FF. For a Levi subgroup LL of GG, write W(G,L)=NG(L)/LW(G,L)=N_G(L)/L. For an inertial equivalence class s=[L,ω]G{\frak s}=[L,\omega]_G, let Irrs(G){\rm Irr}^{\mathfrak s}(G) be the corresponding Bernstein component, let TsT_{\mathfrak s} be its Bernstein torus, let Ts,unT_{{\mathfrak s},{\rm un}} be the unitary subtorus, and let WsW_{\mathfrak s} be the finite stabilizer of TsT_{\mathfrak s}. For a finite group action, Ts/ ⁣/WsT_{\mathfrak s}/\!/W_{\mathfrak s} denotes the extended quotient, with a family of twisting 2-cocycles \natural. Bijection with extended quotients. There exist a family of 2-cocycles \natural and a bijection

Irrs(G)(Ts/ ⁣/Ws){\rm Irr}^{\mathfrak s}(G)\longleftrightarrow (T_{\mathfrak s}/\!/W_{\mathfrak s})_{\natural}

such that its restriction is a bijection

Irrtemps(G)(Ts,un/ ⁣/Ws),{\rm Irr}^{\mathfrak s}_{\rm temp}(G)\longleftrightarrow (T_{{\mathfrak s},{\rm un}}/\!/W_{\mathfrak s})_{\natural},

and this restriction determines the full bijection; moreover, if π\pi maps to [t,ρ][t,\rho], then WstW_{\mathfrak s}t is the unitary part of the cuspidal support of π\pi under the polar decomposition of TsT_{\mathfrak s}. This conjecture proposes a precise parametrization of each Bernstein component by a twisted extended quotient, with tempered representations corresponding to the unitary locus; its status is not resolved in the supplied source.

Sources & referencesView supporting material

Primary source

Anne-Marie Aubert, Paul Baum, Roger Plymen and Maarten Solleveld, “Smooth Duals of Inner Forms of GL_n and SL_n”, arXiv:1505.04361 (2019).

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