Oscillons and bubbles in Q-ball dynamics

A bstract We show that, in the thin-wall regime, Q -ball-anti- Q -ball collisions reveal chaotic behaviour. This is explained by the resonant energy transfer mechanism triggered by the internal modes hosted by the Q -balls and by the existence of ephemeral states, that is unstable, sometimes even short-lived, field configurations that appear as intermediate states. The most important examples of such states are the bubble of the false broken vacuum, which as intermediate states govern the QQ * annihilation, and the charged oscillons . The usually short-lived bubble can be dynamically temporarily stabilized, which explains their importance in the dynamics of Q -balls. This happens due to the excitation of massless Goldstone modes, which, exerting pressure on the bubble boundaries or being trapped as bound modes, prevent the bubble from collapsing.