Vacuum solutions of a gravity model with vector-induced spontaneous Lorentz symmetry breaking

We study the vacuum solutions of a gravity model where Lorentz symmetry is spontaneously broken once a vector field acquires a vacuum expectation value. Results are presented for the purely radial Lorentz symmetry breaking (LSB), radial/temporal LSB and axial/temporal LSB. The purely radial LSB result corresponds to new black hole solutions. When possible, parametrized post-Newtonian parameters are computed and observational boundaries used to constrain the Lorentz symmetry breaking scale.

Figure 1

Allowed values for $K$ and $K_r$, derived from $|\beta -1|\le 6\times {10}^{-4}$, $\gamma =1+(2.1\pm 2.3)\times {10}^{-5}$ and the assumption $|1-K_r/K|\lesssim 0.1$.

Figure 2

Detail of Fig. 1, showing only the allowed region.