Depth-zero base change compatibility for tamely ramified extensions

Let FF be a local field, let E/FE/F be a cyclic tamely ramified extension, and let G\underline{G} be a reductive group over FF. For a point xx in the building of G(F)\underline{G}(F), let GxG_x and G~x\widetilde{G}_x be the corresponding parahoric subgroups, with connected reductive quotients Gx\underline{\mathsf{G}}_x and G~x\widetilde{\underline{\mathsf{G}}}_x over kFk_F. If π\pi contains (Gx,infl(σ))(G_x,\operatorname{infl}(\sigma)), where σ\sigma is an irreducible cuspidal representation of Gx(kF)\underline{\mathsf{G}}_x(k_F), Depth-zero base change compatibility for tame ramification. Suppose there is a base change lifting BCE/F\operatorname{BC}_{E/F} taking LL-packets for G(F)\underline{G}(F) to LL-packets for G(E)\underline{G}(E). For every depth-zero LL-packet Π\Pi for G(F)\underline{G}(F) and πΠ\pi\in\Pi containing (Gx,infl(σ))(G_x,\operatorname{infl}(\sigma)), some π~BCE/F(Π)\widetilde{\pi}\in\operatorname{BC}_{E/F}(\Pi) contains

(G~x,infl(σ~))(\widetilde{G}_x,\operatorname{infl}(\widetilde{\sigma}))

for some irreducible representation σ~\widetilde{\sigma} of G~x(kF)\widetilde{\underline{\mathsf{G}}}_x(k_F) contained in (σ)\ell(\sigma). The assertion proposes a finite-group compatibility even though the reductive quotient need not be obtained by restriction of scalars in the ramified case. The source gives no resolution status for this broader conjecture, so it is recorded as open.

Sources & referencesView supporting material

Primary source

Jeffrey D. Adler and Joshua M. Lansky, “Depth-zero base change for ramified U(2,1)”, arXiv:0807.1528 (2009).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.