INSTABILITIES AND INTERACTIONS OF GLOBAL TOPOLOGICAL DEFECTS

The dynamics of global topological defects are investigated. The stability towards radial rescaling of global monopoles and vortices is verified and virial theorems connecting the potential and gradient energies are obtained. The validity of these theorems is demonstrated numerically. The angular monopole instability first discussed by Goldhaber is also examined. It is shown that even though his are correct, this instability manifests itself as motion of the monopole core rather than unwinding. The interactions of global defects are studied both analytically and numerically. An analytical derivation of their interaction potential is followed by numerical simulation verifying the predicted potential. Using boosted field configurations we demonstrate the existence of critical velocities for defect scattering and annihilation.