Generalized permutation matrices and non-weight modules over $\mathfrak{sl}(m|1)$
Ivan Dimitrov, Khoa Nguyen, Charles Paquette, David Wehlau
TL;DR
The paper addresses the problem of classifying and constructing $U(\mathfrak h)$-free $\mathfrak{sl}(m|1)$-modules of rank $(k|k)$, extending the rank-1 theory to higher ranks. It introduces a robust framework of generalized permutation matrices to realize modules $M(A_1,\dots,A_m)$, and shows how exponential modules $E\big(\sum a_i x_i^{k_i},\mathcal S\big)$ arise as explicit $M$-realizations with precise $h_i$-companion data. A central result is the indecomposability criterion: $E(\sum a_i x_i^{k_i},\mathcal S)$ is indecomposable iff $\gcd(k_1,\dots,k_m)=1$, together with explicit isomorphism criteria and endomorphism descriptions; when the gcd is $s>1$, the module splits into $s$ indecomposable blocks. The work also develops a duality theory for these modules and provides a moduli space description as a finite union of weighted projective spaces, offering a concrete, geometric classification of isomorphism classes. Overall, the results yield new, explicit constructions and a thorough understanding of non-weight $\mathfrak{sl}(m|1)$-modules of finite rank, enriching the representation theory of Lie superalgebras with concrete algebraic and geometric data.
Abstract
We study the category $\mathcal{M}_{\mathfrak{sl}(m|1)}(k|k)$ of $\mathcal U(\mathfrak h)\text{-free}$ $\mathcal U(\mathfrak{sl}(m|1))$-modules of rank $k$ in each parity (rank $(k|k)$), where $k\in\mathbb{Z}_{\geq1}$. We construct an explicit family of such modules, provide an isomorphism theorem, and establish an indecomposability criterion.
