Langlands correspondence for reductive groups over finite fields

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Let GG be a reductive group over the finite field kk, let G∨G^{\vee} be its dual group, and let ℓ\ell be a prime distinct from the characteristic of kk. Write Irr⁡Q‾ℓ(G(k))\operatorname{Irr}_{\overline{\mathbb{Q}}_{\ell}}(G(k)) for the irreducible Q‾ℓ\overline{\mathbb{Q}}_{\ell}-representations of G(k)G(k), and let ΦQ‾ℓ(G)sp\Phi_{\overline{\mathbb{Q}}_{\ell}}(G)_{\mathrm{sp}} denote the equivalence classes of special Frobenius-semisimple LL-parameters. For φ∈ΦQ‾ℓ(G)sp\varphi\in\Phi_{\overline{\mathbb{Q}}_{\ell}}(G)_{\mathrm{sp}}, put Aφ=ZA‾(φ0)(φ(σq)‾)A_{\varphi}=Z_{\overline{A}(\varphi_0)}(\overline{\varphi(\sigma_q)}), with φ0=φ∣Ga×Ik\varphi_0=\varphi|_{\mathbb{G}_{\mathrm{a}}\times I_k}. Langlands correspondence. There is a natural map

LG ⁣:Irr⁡Q‾ℓ(G(k))→ΦQ‾ℓ(G)sp\mathcal{L}_G\colon \operatorname{Irr}_{\overline{\mathbb{Q}}_{\ell}}(G(k))\to\Phi_{\overline{\mathbb{Q}}_{\ell}}(G)_{\mathrm{sp}}

such that, for φ∈ΦQ‾ℓ(G)sp\varphi\in\Phi_{\overline{\mathbb{Q}}_{\ell}}(G)_{\mathrm{sp}}, there is a bijection between LG−1(φ)\mathcal{L}_G^{-1}(\varphi) and Irr⁡Q‾ℓ(Aφ)\operatorname{Irr}_{\overline{\mathbb{Q}}_{\ell}}(A_{\varphi}). This formulates the expected parametrization of irreducible representations of G(k)G(k) by special Langlands parameters together with irreducible representations of the associated component group; the supplied material does not establish whether the statement has been proved or remains open.

References

Primary source

Naoki Imai and David A. Vogan, “Langlands parameters for reductive groups over finite fields”, arXiv:2506.06961 (2025).

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