Proca Q-balls and Q-shells

TL;DR

This paper extends the study of non-topological solitons to include a Proca mass for the gauge boson, revealing novel features like disconnected parameter regions and unbounded Q-shells, supported by numerical and analytical solutions.

Contribution

It introduces a generalized framework for Q-balls and Q-shells with Proca gauge bosons, uncovering new phenomena and providing both numerical and analytical insights.

Findings

Proca mass leads to unique soliton features.

Numerical solutions match analytical approximations.

Discovery of Q-shells with unbounded radius.

Abstract

Non-topological solitons such as Q-balls and Q-shells have been studied for scalar fields invariant under global and gauged U(1) symmetries. We generalize this framework to include a Proca mass for the gauge boson, which can arise either from spontaneous symmetry breaking or via the St\"uckelberg mechanism. A heavy (light) gauge boson leads to solitons reminiscent of the global (gauged) case, but for intermediate values these Proca solitons exhibit completely novel features such as disconnected regions of viable parameter space and Q-shells with unbounded radius. We provide numerical solutions and excellent analytic approximations for both Proca Q-balls and Q-shells. These allow us to not only demonstrate the novel features numerically, but also understand and predict their origin analytically.