Aspects of the BMS/CFT correspondence

Abstract

We review recent results on symmetries of asymptotically flat spacetimes at null infinity. In higher dimensions, the symmetry algebra realizes the Poincar´ e algebra. In three and four dimensions, besides the infinitesimal supertranslations that have been known since the sixties, the algebras are evenly balanced because there are also infinitesimal superrotations. We provide the classification of central extensions of bms3 and bms4. Applications and consequences as well as directions for future work are briefly indicated.