The torus-torsor extension conjecture for Γ1(p)\Gamma_1(p)-level covers

Assume the divisor conjecture and let π:ShK1(G,X)E\ifbool@displayShK0(G,X)E\pi:{\rm Sh}_{K_1}(G,X)_E% \ifbool{@display}{\longrightarrow}{\rightarrow}% {\rm Sh}_{K_0}(G,X)_E be the generic-fiber TG(Fp)T_{\mathcal G}(\mathbb F_p)-torsor, represented by a pair (Qπ,aπ)(Q_\pi,a_\pi). Let SK0{\mathcal S}_{K_0} be the integral model with local-model morphism φ\varphi. The torus-torsor extension conjecture. There \exists a TGT_{\mathcal G}-torsor PP over SK0{\mathcal S}_{K_0}, an isomorphism P[1/p]QπP[1/p]\simeq Q_\pi, and an isomorphism of pairs

(L(P),L(α1)aπ)φ(PG,μ(1),sG,μ).\bigl(L_*(P),L_*(\alpha^{-1})\circ a_\pi\bigr)\simeq\varphi^*\bigl({\rm P}^{(-1)}_{{\mathcal G},\mu},s_{{\mathcal G},\mu}\bigr).

This is the proposed torsorial construction underlying the global integral model at Γ1(p)\Gamma_1(p)-level; it is stated conditionally on the divisor conjecture and is not resolved in the source.

Sources & referencesView supporting material

Primary source

Georgios Pappas and Michael Rapoport, “Toric schemes and integral models for Shimura varieties with Γ_1(p)-type level”, arXiv:2602.23245 (2026).

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