1211.7296 (Pietro Galli et al.)

The Freudenthal gauge symmetry of the black holes of N=2,d=4
supergravity    [PDF]

Pietro Galli, Patrick Meessen, Tomas Ortin

We show that the representation of black-hole solutions in terms of the variables H^M which are harmonic functions in the supersymmetric case is non-unique due to the existence of a local symmetry in the effective action. This symmetry is a continuous (and local) generalization of the discrete Freudenthal transformations initially introduced for the black-hole charges and can be used to rewrite the physical fields of a solution in terms of entirely different-looking functions.

View original: http://arxiv.org/abs/1211.7296