Arithmetic level raising, self-dual case

In the indefinite case, let S0\mathcal{S}_0^\circ be the relevant Shimura variety, let S~0\widetilde{\mathcal{S}}_0^\circ be its special fiber, let S0\mathrm{S}'_0 parameterize the irreducible components of its basic locus, and let n0\mathfrak{n}_0 be the localization ideal. Let nn, rr, λ\lambda, Π0,p\Pi_{0,\mathfrak{p}}, and V0,λΠ\mathrm{V}^\Pi_{0,\lambda} be as in the source. Arithmetic level raising, self-dual case. If (a) Hi(S0FQ,Zλ)n0=0\mathrm{H}^i(\mathcal{S}_0^\circ\otimes_F\overline{\mathbb{Q}},\mathbb{Z}_\lambda)_{\mathfrak{n}_0}=0 for in1i\neq n-1 and Hn1(S0FQp,Zλ)n0\mathrm{H}^{n-1}(\mathcal{S}_0^\circ\otimes_F\overline{\mathbb{Q}}_p,\mathbb{Z}_\lambda)_{\mathfrak{n}_0} is finite free over Zλ\mathbb{Z}_\lambda, (b) V0,λΠ\mathrm{V}^\Pi_{0,\lambda} is residually absolutely irreducible, and (c) the Satake parameter of Π0,p\Pi_{0,\mathfrak{p}} modulo λ\lambda contains pp at most once, then the localized absolute cycle class map

Zλ[S0]n0H2r(S~0,Zλ(r))n0\mathbb{Z}_\lambda[\mathrm{S}'_0]_{\mathfrak{n}_0}\longrightarrow \mathrm{H}^{2r}(\widetilde{\mathcal{S}}_0^\circ,\mathbb{Z}_\lambda(r))_{\mathfrak{n}_0}

is surjective. This generalizes Ribet’s level-raising theorem for modular curves, or the corresponding unitary Shimura curves, at good places; the assertion itself is presented as a conjecture.

Sources & referencesView supporting material

Primary source

Yifeng Liu, Yichao Tian, Liang Xiao, Wei Zhang and Xinwen Zhu, “Survey on bounding Selmer groups for Rankin–Selberg motives”, arXiv:2509.16881 (2025).

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