BMS Modules in Three Dimensions

Abstract

We build unitary representations of the BMS algebra and its higher-spin extensions in three dimensions, using induced representations as a guide. Our prescription naturally emerges from an ultrarelativistic limit of highest-weight representations of Virasoro and W algebras, which is to be contrasted with non-relativistic limits that typically give non-unitary representations. To support this dichotomy, we also point out that the ultrarelativistic and non-relativistic limits of generic W algebras differ in the structure of their non-linear terms.

27 pages; contribution to the proceedings of the workshop "Higher Spin Gauge Theories", Institute for Advanced Studies, NTU, Singapore, November 4-6, 2015