Oscillons, extremely long-lived localized oscillations of a scalar field, are shown to be produced by evolving domain wall networks in ${\varphi }^4$ theory in two spatial dimensions. We study the oscillons in frequency space using the classical spectral function at zero momentum, and obtain that the velocity distribution is suppressed as ${\gamma }^{-2}$ at large Lorentz factor $\gamma$, with oscillons produced up to at least $\gamma \sim 10$. This leads us to speculate that oscillons are produced at cusps, regions of the domain wall travelling near the speed of light. In order to gain some insight onto the dilute oscillon “gas” produced by the domain walls, we prepare a denser gas by filling the simulation volume with oscillons boosted in random directions. We finish the study by revisiting collisions between oscillons and between an oscillon and a domain wall, showing that in the latter case they can pass straight through with minimal distortion.

• Received 11 February 2008

DOI:https://doi.org/10.1103/PhysRevD.77.105025