On Carrollian and Galilean contractions of BMS algebra in 3 and 4 dimensions

Abstract: In this paper, we find a class of Carrollian and Galilean contractions of (extended) BMS algebra in 3+1 and 2+1 dimensions. To this end, we investigate possible embeddings of 3D/4D Poincar\'{e} into the BMS${}_3$ and BMS${}_4$ algebras, respectively. The contraction limits in the 2+1-dimensional case are then enforced by appropriate contractions of its Poincar\'{e} subalgebras. In 3+1 dimensions, we have to apply instead the analogy between the structures of Poincar\'{e} and BMS algebra. In the case of non-vanishing cosmological constant in 2+1 dimensions, we consider the contractions of $\Lambda$-BMS${}_3$ algebra in an analogous manner.