A class of non-weight modules over the super-BMS$_3$ algebra (1911.09651v5)

Abstract: In the present paper, a class of non-weight modules over the super-BMS$_3$ algebras $\S^{\epsilon}$ ($\epsilon=0$ or $\frac{1}{2}$) are constructed. Assume that $\mathfrak{t}=\C L_0\oplus\C W_0\oplus\C G_0$ and $\mathfrak{T}=\C L_0\oplus\C W_0$ are the Cartan subalgebra (modulo center) of $\S^{0}$ and $\S^{\frac{1}{2}}$, respectively. These modules over $\S^{0}$ when restricted to the $\mathfrak{t}$ are free of rank $1$, while these modules over $\S^{\frac{1}{2}}$ when restricted to the $\mathfrak{T}$ are free of rank $2$. Then we determine the necessary and sufficient conditions for these modules being simple, as well as determining the necessary and sufficient conditions for two $\S^{\epsilon}$-modules being isomorphic. %Moreover, we see that the category of free $U(\mathfrak{t})$-modules of rank $1$ over $\S^0$ is %equivalent to the category of free $U(\mathfrak{T})$-modules of rank $2$ over %$\S^{\frac{1}{2}}$.