What are universal features of gravitating Q-balls?

Abstract

We investigate how gravity affects Q-balls by exemplifying the case of the Affleck-Dine potential $V(\phi):=m^4 \ln (1+\frac{\phi^2}{m^2})$. Surprisingly, stable Q-balls with arbitrarily small charge exist, no matter how weak gravity is, contrary to the case of flat spacetime. We also show analytically that this feature holds true for general models as long as the leading order term of the potential is a positive mass term in its Maclaurin series.