The L-packets conjecture for Bernstein components

Let FF be a non-archimedean local field, GG a connected reductive algebraic group over FF, and s=[L,ω]G{\mathfrak s}=[L,\omega]_G an inertial equivalence class. Let TsT_{\mathfrak s} be the Bernstein torus, WsW_{\mathfrak s} its finite stabilizer, and suppose a bijection Irrs(G)(Ts/ ⁣/Ws)\operatorname{Irr}^{\mathfrak s}(G)\leftrightarrow (T_{\mathfrak s}/\!/W_{\mathfrak s})_{\natural} as above. For tTst\in T_{\mathfrak s}, let Ws,tW_{{\mathfrak s},t} be its isotropy group, with decomposition Ws,t=W(Rs,t)Rs,tW_{{\mathfrak s},t}=W(R_{{\mathfrak s},t})\rtimes {\mathfrak R}_{{\mathfrak s},t}, where Rs,tR_{{\mathfrak s},t} is the associated root system. L-packets. Assume that a local Langlands correspondence exists for Irrs(G)\operatorname{Irr}^{\mathfrak s}(G). Then the twisting cocycle factors through Ws,t/W(Rs,t)W_{{\mathfrak s},t}/W(R_{{\mathfrak s},t}), the bijection is canonical up to permutations within L-packets, and two representations with images [t,ρ][t,\rho] and [t,ρ][t',\rho'] lie in the same L-packet exactly when there is wWsw\in W_{\mathfrak s} with wt=twt'=t and the corresponding Springer parameters have the same unipotent class. The conjecture refines the extended-quotient parametrization by predicting how its parameters organize into L-packets; the supplied source gives no resolution status.

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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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