On Integrality of Non-Semisimple Quantum Representations of Mapping Class Groups

Abstract: For a root of unity $\zeta$ of odd prime order, we restrict coefficients of non-semisimple quantum representations of mapping class groups associated with the small quantum group $\mathfrak{u}_\zeta \mathfrak{sl}_2$ from $\mathbb{Q}(\zeta)$ to $\mathbb{Z}[\zeta]$. We do this by exhibiting explicit bases of states spaces that span $\mathbb{Z}[\zeta]$-lattices that are invariant under projective actions of mapping class groups.