The non-abelian Leopoldt conjecture for eigenvariety components

Let GG be a reductive group, let KpG(Afp)K^p\subset G(\mathbb{A}_f^p) be a tame level, let IwG(Qp)\operatorname{Iw}\subset G(\mathbb{Q}_p) be an Iwahori subgroup, and set K=KpIwK=K^p\operatorname{Iw}. Let XG,K\mathcal{X}_{G,K} and XG,Kε\mathcal{X}_{G,K}^{\varepsilon} be the corresponding eigenvarieties over the weight space W\mathcal{W}, and let (G)\ell(G) denote the defect of GG. For a non-critical classical tempered cuspidal eigenpacket ϕ\phi, write xϕx_\phi for the associated point. The non-abelian Leopoldt conjecture. Any irreducible component IXG,K\mathcal{I}\subset\mathcal{X}_{G,K}, or XG,Kε\mathcal{X}_{G,K}^{\varepsilon}, through xϕx_\phi has dimension

dimW(G).\dim \mathcal{W}-\ell(G).

This predicts that the defect measures the codimension of cuspidal eigenvariety components in the weight space, extending the usual Leopoldt philosophy to non-abelian eigenvarieties. The conjecture is attributed to Hida and Urban; the supplied text gives no evidence of a general resolution.

Sources & referencesView supporting material

Primary source

Daniel Barrera Salazar, Andrew Graham and Chris Williams, “The non-abelian Leopoldt conjecture and equalities of L-invariants”, arXiv:2603.18961 (2026).

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