Towards the correspondence between Q-clouds and sphalerons

Abstract

Non-linear classical equations of motion may admit degenerate solutions at fixed charges. While the solutions with lower energies are classically stable, the ones with larger energies are unstable and refereed as Q-clouds. We consider a theory in which the homogeneous charged condensate is classically stable and argue that Q-clouds correspond to sphalerons between the stable Q-balls and the condensate. For the model with analytic solution, we present Arrhenius formula for the quantum production of Q-balls from the condensate at large temperatures.