Oscillons and quasi-breathers in D+1 dimensions

We study oscillons in D+1 space-time dimensions using a spherically symmetric ansatz. From Gaussian initial conditions, these evolve by emitting radiation, approaching ``quasi-breathers'', near-periodic solutions to the equations of motion. Using a truncated mode expansion, we numerically determine these quasi-breather solutions in 2<D<6 and the energy dependence on the oscillation frequency. In particular, this energy has a minimum, which in turn depends on the number of spatial dimensions. We study the time evolution and lifetimes of the resulting quasi-breathers, and show how generic oscillons decay into these before disappearing altogether. We comment on the apparent absence of oscillons for D>5 and the possibility of stable solutions for D<2.