On graded representations of modular Lie algebras over commutative algebras

Abstract

We develop the theory of a category ${\mathscr C}_A$ which is a generalisation to non-restricted ${\mathfrak g}$-modules of a category famously studied by Andersen, Jantzen and Soergel for restricted ${\mathfrak g}$-modules, where ${\mathfrak g}$ is the Lie algebra of a reductive group $G$ over an algebraically closed field ${\mathbb K}$ of characteristic $p>0$. Its objects are certain graded bimodules. On the left, they are graded modules over an algebra $U_\chi$ associated to ${\mathfrak g}$ and to $\chi\in{\mathfrak g}^{*}$ in standard Levi form. On the right, they are modules over a commutative Noetherian $S({\mathfrak h})$-algebra $A$, where ${\mathfrak h}$ is the Lie algebra of a maximal torus of $G$. We develop here certain important modules $Z_{A,\chi}(\lambda)$, $Q_{A,\chi}^I(\lambda)$ and $Q_{A,\chi}(\lambda)$ in ${\mathscr C}_A$ which generalise familiar objects when $A={\mathbb K}$, and we prove some key structural results regarding them.