The mod pp Langlands lifting and automorphy conjecture for global fields

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Let FF be a global field of characteristic different from pp. Let GG be a connected reductive group, and let G′G' be the split group over FF whose root datum is dual to that of GG. Let SS be a finite set of primes of FF, containing all primes above pp when FF is a number field, and let

ρˉ ⁣:ΓF,S→G(k)\bar{\rho} \colon \Gamma_{F,S} \to G(k)

be a continuous representation unramified outside SS. If FF is a number field, assume further that it is totally real and that ρˉ\bar{\rho} is odd. Mod pp Langlands lifting and automorphy conjecture. There is a lift

ρ ⁣:ΓF→G(O)\rho \colon \Gamma_F \to G(\mathcal{O})

of ρˉ\bar{\rho} to the ring of integers O\mathcal{O} in some finite extension of Qp\mathbb{Q}_p inside Q‾p\overline{\mathbb{Q}}_p, unramified outside a finite set of primes, with Zariski-dense image in GG and, in the number field case, regular Hodge--Tate cocharacters. There are also an LL-algebraic cuspidal automorphic representation π\pi of G′(AF)G'(\mathbb{A}_F) and an isomorphism ι ⁣:C→Q‾p\iota \colon \mathbb{C} \to \overline{\mathbb{Q}}_p such that the conjectural Galois representation

ρπ,ι ⁣:ΓF→G(Q‾p)\rho_{\pi,\iota} \colon \Gamma_F \to G(\overline{\mathbb{Q}}_p)

associated to (π,ι)(\pi,\iota) is isomorphic to ρ ⁣:ΓF→G(O)⊂G(Q‾p)\rho \colon \Gamma_F \to G(\mathcal{O}) \subset G(\overline{\mathbb{Q}}_p). Moreover, if ρˉ\bar{\rho} is absolutely irreducible, ρ\rho and π\pi can be taken to be unramified outside SS. In the function field case, the automorphic Galois representation construction is known by V. Lafforgue for general GG; in the number field case, the conjecture concerns automorphic Galois representations expected to have regular infinitesimal character, and remains open in general.

References

Primary source

Najmuddin Fakhruddin, Chandrashekhar Khare and Stefan Patrikis, “Lifting and automorphy of reducible mod p Galois representations over global fields”, arXiv:2008.12593 (2021).

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