Gross's newform conjecture for generic representations of split odd special orthogonal groups

From papers

Let FF) be a finite extension of Qp\mathbb{Q}_p, and let SO2n+1(F){\rm SO}_{2n+1}(F) be the split odd special orthogonal group. Let Kn,mK_{n,m} and Jn,mJ_{n,m} be Gross's families of open compact subgroups, with Kn,0=Jn,0K_{n,0}=J_{n,0} and Kn,mK_{n,m} a normal subgroup of Jn,mJ_{n,m} of index 22 for m1m\geq 1. Let Un(F)U_n(F) be the maximal unipotent subgroup, and fix the non-degenerate character ψUn\psi_{U_n} defined from an unramified additive character ψ\psi of FF. For an irreducible generic representation π\pi of SO2n+1(F){\rm SO}_{2n+1}(F), let ϕπ\phi_\pi be its associated LL-parameter and write

ϵ(s,ϕπ,ψ)=επqcπ(s12),\epsilon(s,\phi_\pi,\psi)=\varepsilon_\pi q^{-c_\pi(s-\frac12)},

where επ{±1}\varepsilon_\pi\in\{\pm1\}, cπ0c_\pi\geq 0, and qq is the residue-field cardinality.

Gross's conjecture. The following assertions hold: πKn,m=0\pi^{K_{n,m}}=0 for 0m<cπ0\leq m<c_\pi and dimCπKn,cπ=1\dim_\mathbb{C}\pi^{K_{n,c_\pi}}=1; the action of Jn,cπ/Kn,cπJ_{n,c_\pi}/K_{n,c_\pi} on πKn,cπ\pi^{K_{n,c_\pi}} is the scalar επ\varepsilon_\pi; and the natural pairing

HomKn,cπ(1,π)×HomUn(F)(π,ψUn)C\operatorname{Hom}_{K_{n,c_\pi}}(1,\pi)\times\operatorname{Hom}_{U_n(F)}(\pi,\psi_{U_n})\longrightarrow\mathbb{C}

is non-degenerate.

This is the newform conjecture for generic representations of SO2n+1(F){\rm SO}_{2n+1}(F). The paper states that the existence part remains conditional because of unresolved issues in earlier proofs; the conjecture is therefore not established in the cited literature.

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Sources & referencesView supporting material

Primary source

Yao Cheng, “Local newforms for generic representations of p-adic SO_2n+1: Reduction”, arXiv:2605.15678 (2026).

Additional references

2 papers in this index state this conjecture (2025–2026). The statement above is taken from the most recent of them; the others are arXiv:2510.03068.

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