Towards the correspondence between Q-clouds and sphalerons

Understand

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.