Vacuum Branching, Dark Energy, Dark Matter
Beginning with the Everett-DeWitt many-worlds interpretation of quantum mechanics, there have been a series of proposals for how the state vector of a quantum system might split at any instant into orthogonal branches, each of which exhibits approximately classical behavior. In an earlier version of the present work, we proposed a decomposition of a state vector into branches by finding the minimum of a measure of the mean squared quantum complexity of the branches in the branch decomposition. In the present article, we adapt the earlier version to quantum electrodynamics of electrons and protons on a lattice in Minkowski space. The earlier version, however, here is simplified by replacing a definition of complexity based on the physical vacuum with a definition based on the bare vacuum. As a consequence of this replacement, the physical vacuum itself is expected to branch yielding branches with energy densities slightly larger than that of the unbranched vacuum but no observable particle content. If the vacuum energy renormalization constant is chosen as usual to give 0 energy density to the unbranched vacuum, vacuum branches will appear to have a combination of dark energy and dark matter densities. The hypothesis that vacuum branching is the origin of the observed dark energy and dark matter densities leads to an estimate of $O(10^{-18} m^3)$ for the parameter $b$ which enters the complexity measure governing branch formation and sets the boundary between quantum and classical behavior.