Supercooling exit from charge supersaturation

Abstract

Systems that feature a scalar field $\phi$ with a quasi scale invariant potential, metastable at $\phi=0$, can remain trapped, during cosmic evolution, in the `wrong' vacuum because the process of bubble nucleation to the true vacuum is inefficient. If $\phi$ carries a conserved charge $Q$, the presence in the system of a non-zero chemical potential for $Q$ offers the possibility of escaping eternal supercooling: when a species decouples from the plasma the balance among the stabilising effect of temperature and the destabilising effect of chemical potential can change in favour of the latter, so that $\phi$ condenses and triggers the transition to the stable phase.