Q-Monopole-Ball: A Topological and Nontopological Soliton

Abstract

Magnetic monopoles and Q-balls are examples of topological and nontopological solitons, respectively. A new soliton state with both topological and nontopological charges is shown to also exist, given a monopole sector with a portal coupling to an additional scalar field $S$ with a global $U(1)$ symmetry. This new state, the Q-monopole-ball, is more stable than an isolated Q-ball made of only $S$ particles, and it could be stable against fissioning into monopoles and free $S$ particles. Stable Q-monopole-balls can contain large magnetic charges, providing a novel nongravitational mechanism for binding like-charged monopoles together. They could be produced from a phase transition in the early universe and account for all dark matter.