  Physics beyond the Standard Model is an important candidate for dark matter,
and an interesting testing ground for strong-field gravity: the equivalence
principle "forces" all forms of matter to fall in the same way, and it is
therefore natural to look for imprints of these fields in regions with strong
gravitational fields, such as compact stars or black holes. Here we study
General Relativity minimally coupled to a massive vector field, and how black
holes in this theory lose "hair". Our results indicate that black holes can
sustain Proca field condensates for extremely long time-scales.
