Multi-Field Q-balls with Real Scalars

Abstract: Multi-field Q-balls, in which some, but not all, of the constituent fields are real scalars, are studied. Uncharged fields may classically contribute to Q-balls provided that their effect is to not destabilise the resulting object. The thin-wall limit is reviewed based on existing literature. Sufficient conditions for the theories that can plausibly contain thick-wall solutions are derived. Necessary conditions require a detailed numerical analysis, outside the scope of this work. These conditions show that when the additional real scalars are massive, a minimum charge must accumulate in order to render the Q-ball energetically stable.