Grassmanniennes affines tordues sur les entiers (vol 11, pg E12, 2023)

Summary: This paper generalizes the previous works on twisted affine Grassmannians to the wildly ramified case, with mild assumptions. It constructs smooth affine $\mathbb {Z}[t]$-groups with connected fibers of parahoric type, motivated by previous work of Tits. The resulting $\mathbb {F}_p(t)$-groups are pseudo-reductive and sometimes non-standard, and their $\mathbb {F}_p [\hspace{-0.5mm}[ {t} ]\hspace {-0.5mm}]$-models are parahoric in a generalized sense. The paper also studies their affine Grassmannians and proves the normality of Schubert varieties and Zhu's coherence theorem.