Geodesic evolution and nucleation of a de Sitter brane

Within the framework of geodesic brane gravity, the deviation from general relativity is parametrized by the conserved bulk energy. The corresponding geodesic evolution/nucleation of a de Sitter brane is shown to be exclusively driven by a double-well Higgs potential, rather than by a plain cosmological constant. The (hairy) horizon serves then as the locus of unbroken Z2 symmetry. The quartic structure of the scalar potential, singled out on finiteness grounds of the total (including the dark component) energy density, chooses the Hartle-Hawking no-boundary proposal.