Central charges in the canonical realization of asymptotic symmetries: An example from three dimensional gravity
Abstract
It is shown that the global charges of a gauge theory may yield a nontrivial central extension of the asymptotic symmetry algebra already at the classical level. This is done by studying three dimensional gravity with a negative cosmological constant. The asymptotic symmetry group in that case is either R×SO(2) or the pseudoconformal group in two dimensions, depending on the boundary conditions adopted at spatial infinity. In the latter situation, a nontrivial central charge appears in the algebra of the canonical generators, which turns out to be just the Virasoro central charge.
 Publication:

Communications in Mathematical Physics
 Pub Date:
 June 1986
 DOI:
 10.1007/BF01211590
 Bibcode:
 1986CMaPh.104..207B