2012/05/31 by Carlo Rovelli, Edward Wilson-Ewing · 1 citation
Physics and Astronomy · #gr-qc
paper · pdf · doi:10.1103/physrevd.86.064002
published as Phys.Rev.D86:064002,2012 · 8 pages, v2: Minor changes
arxiv created 2012/07/30 · arxiv updated 2013/05/29
We study time-reversal and parity ---on the physical manifold and in internal space--- in covariant loop gravity. We consider a minor modification of the Holst action which makes it transform coherently under such transformations. The classical theory is not affected but the quantum theory is slightly different. In particular, the simplicity constraints are slightly modified and this restricts orientation flips in a spinfoam to occur only across degenerate regions, thus reducing the sources of potential divergences.