Symmetries of Asymptotically Flat FourDimensional Spacetimes at Null Infinity Revisited
Abstract
It is shown that the symmetry algebra of asymptotically flat spacetimes at null infinity in 4 dimensions should be taken as the semidirect sum of supertranslations with infinitesimal local conformal transformations and not, as usually done, with the Lorentz algebra. As a consequence, twodimensional conformal field theory techniques will play as fundamental a role in this context of direct physical interest as they do in threedimensional antide Sitter gravity.
 Publication:

Physical Review Letters
 Pub Date:
 September 2010
 DOI:
 10.1103/PhysRevLett.105.111103
 arXiv:
 arXiv:0909.2617
 Bibcode:
 2010PhRvL.105k1103B
 Keywords:

 04.20.Ha;
 04.60.m;
 Asymptotic structure;
 Quantum gravity;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 7 pages Latex file, references added, comments on Poincare algebra and angular momentum added