Bartnik and McKinnon generalize from the Abelian gauge group to the non-Abelian group and thereby find these unexpected particle-like solutions. One can consider, as does Ref.  (see Section IIp), these globally regular solutions (and their generalizations to for ) as gauged boson stars even though these contain no scalar field. One can instead explicitly include a scalar field doublet coupled to the Yang–Mills gauge field  as perhaps a more direct generalization of the () charged boson stars discussed in Section 3.3.
Ref.  studies BSs formed from a gauge condensate of an gauge field, and Ref.  extends the Bartnik–McKinnon solutions to conformal gravity with a Higgs field .
Living Rev. Relativity 15, (2012), 6
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