Monopole solutions in SU(2) Yang-Mills theory which interact with massive nonlinear spinor fields described by the nonlinear Dirac equation are obtained. These solutions describe a magnetic monopole created by a spherical lump of nonlinear spinor fields.
It is shown that the monopole solutions obtained differs in principle from the ’t Hooft-Polyakov monopole so that its: (а) topologically trivial; (b) the radial magnetic field of which decreases as r-3 ; (c) for its existence no need the Higgs field.
It is demonstrated that the energy spectrum of such a system possesses a global minimum, the appearance of which is due exclusively to the nonlinearity of the Dirac spinor fields. This global minimum can be considered as a mass gap, i.e. the energy difference between a vacuum and the next lowest energy state. A similar minimum was found for the energy spectrum of regular solutions to the nonlinear Dirac equation and this minimun called as “the lightest stable particle”.
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