Conjecture on the unramified Langlands correspondence and elliptic pairings

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Let GG be a reductive group, let C(G∨)ss{\mathcal C}(G^\vee)_{\mathsf{ss}} be the set of semisimple conjugacy classes in the dual group, and for s∈C(G∨)sss\in{\mathcal C}(G^\vee)_{\mathsf{ss}} and unipotent u∈C(Gs)unu\in{\mathcal C}({\mathcal G}_s)_{\mathrm{un}} let AGs(u)A_{{\mathcal G}_s}(u) be the relevant component group. Let R‾(AGs(u))\overline R(A_{{\mathcal G}_s}(u)) denote its elliptic quotient, and let R‾un(G′)\overline R_{\mathrm{un}}(G') denote the elliptic quotient of the unipotent representation ring of an inner twist G′G'. Unramified Langlands correspondence conjecture. The unramified Langlands correspondence induces isometric isomorphisms

LLC‾un ⁣:⨁s∈C(G∨)ss⨁u∈C(Gs)unR‾(AGs(u))⟶⨁G′∈InnT(G)R‾un(G′),\overline{\mathsf{LLC}}_{{\mathrm{un}}}\colon \bigoplus_{s\in {\mathcal C}(G^\vee)_{\mathsf{ss}}}\bigoplus_{u\in {\mathcal C}({\mathcal G}_s)_{{\mathrm{un}}}}\overline R(A_{{\mathcal G}_s}(u))\longrightarrow \bigoplus_{G'\in{\mathrm{InnT}}(G)}\overline R_{{\mathrm{un}}}(G'),

and

LLCp‾un ⁣:⨁s∈C(G∨)ss⨁u∈C(Gsp)unR‾(AGsp(u))⟶⨁G′∈Innp(G)R‾un(G′),\overline{\mathsf{LLC}^p}_{{\mathrm{un}}}\colon \bigoplus_{s\in {\mathcal C}(G^\vee)_{\mathsf{ss}}}\bigoplus_{u\in {\mathcal C}({\mathcal G}_s^p)_{{\mathrm{un}}}}\overline R(A_{{\mathcal G}_s^p}(u))\longrightarrow \bigoplus_{G'\in{\mathrm{Inn}}^p(G)}\overline R_{{\mathrm{un}}}(G'),

where the left-hand spaces have the elliptic inner products ( , )ellδus(~,~)^{\delta_u^s}_{\mathrm{ell}} and the right-hand spaces have the Euler–Poincaré pairings EPG′{\mathrm{EP}}_{G'}. This conjecture predicts compatibility between the elliptic representation-theoretic and Langlands-parameter descriptions, but the supplied text gives no resolution evidence.

References

Primary source

Anne-Marie Aubert, Dan Ciubotaru and Beth Romano, “A nonabelian Fourier transform for tempered unipotent representations”, arXiv:2106.13969 (2024).

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