Definition of Spin Charge in Asymptotically-Flat Spacetimes

Explore a groundbreaking solution to a longstanding problem in gravitational physics concerning the definition of spin in asymptotically-flat spacetimes. Delve into the proposed approach using the generalized-BMS algebra (gbms) instead of the traditional BMS algebra. Examine the construction of Casimir invariants for gbms coadjoint orbits and the introduction of spin charge as the generator of its isotropy subalgebra. Investigate the parallels between this analysis and the Poincaré case, including the clarification of Poincaré embedding in gbms and the concept of rest frame. Discover the construction of a gravitational analog to the Pauli-Lubánski pseudo-vector from the spin generator. This 56-minute talk, presented by Daniele Pranzetti at the Erwin Schrödinger International Institute for Mathematics and Physics, was part of the Thematic Programme on "Carrollian Physics and Holography" in April 2024.