Ehlers symmetry at the next derivative order
arXiv:0706.2816 · doi:10.1088/1126-6708/2007/08/078
Abstract
We analyse four-dimensional gravity in the presence of general curvature squared corrections and show that Ehlers' SL(2,R) symmetry, which appears in the reduction of standard gravity to three dimensions, is preserved by the correction terms. The mechanism allowing this is a correction of the SL(2,R) transformation laws which resolves problems with the different scaling behaviour of various terms occurring in the reduction.
13 pages. v2: updated reference