Most general flat space boundary conditions in threedimensional Einstein gravity
Abstract
We consider the most general asymptotically flat boundary conditions in threedimensional Einstein gravity in the sense that we allow for the maximal number of independent free functions in the metric, leading to six towers of boundary charges and six associated chemical potentials. We find as associated asymptotic symmetry algebra an isl(2)_{k} current algebra. Restricting the charges and chemical potentials in various ways recovers previous cases, such as bms_{3} , Heisenberg or DetournayRiegler, all of which can be obtained as contractions of corresponding AdS_{3} constructions. Finally, we show that a flat space contraction can induce an additional Carrollian contraction. As examples we provide two novel sets of boundary conditions for Carroll gravity.
 Publication:

Classical and Quantum Gravity
 Pub Date:
 September 2017
 DOI:
 10.1088/13616382/aa8004
 arXiv:
 arXiv:1704.07419
 Bibcode:
 2017CQGra..34r4001G
 Keywords:

 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology
 EPrint:
 23 pp, invited for CQG BMS Focus Issue edited by Geoffrey Compere, v2: added minor clarifications and refs