ChernSimons modification of general relativity
Abstract
General relativity is extended by promoting the threedimensional gravitational ChernSimons term to four dimensions. This entails choosing an embedding coordinate v_{μ}—an external quantity, which we fix to be a nonvanishing constant in its time component. The theory is identical to one in which the embedding coordinate is itself a dynamical variable, rather than a fixed, external quantity. Consequently diffeomorphism symmetry breaking is hidden in the modified theory: the Schwarzschild metric is a solution; gravitational waves possess two polarizations, each traveling at the velocity of light; a conserved energymomentum (pseudo)tensor can be constructed. The modification is visible in the intensity of gravitational radiation: the two polarizations of a gravity wave carry intensities that are suppressed or enhanced by the extension.
 Publication:

Physical Review D
 Pub Date:
 November 2003
 DOI:
 10.1103/PhysRevD.68.104012
 arXiv:
 arXiv:grqc/0308071
 Bibcode:
 2003PhRvD..68j4012J
 Keywords:

 04.20.Cv;
 04.50.+h;
 Fundamental problems and general formalism;
 Gravity in more than four dimensions KaluzaKlein theory unified field theories;
 alternative theories of gravity;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 19 pages, added references, an addition in section 5