Excitations in antiferromagnetic cores of superconducting vortices

We study excitations of the predicted antiferromagnetically ordered vortex cores in the superconducting phase of the newly proposed SO(5) model of str ongly correlated electrons. Using experimental data from the literature we show that the susceptibilities in the spin sector and the charge sector an nearly equal, and likewise for the stiffnesses. In the case of strict equal ity SO(5) symmetry is possible, and we find that if present the vortices gi ve rise to an enhanced neutron scattering cross section near the so called pi resonance at 41 meV. In the case of broken SO(5) symmetry two effects ar e predicted. Bound excitations can exist in the vortex cores with "high" ex citation energies slightly below 41 meV, and the massless Goldstone modes c orresponding to the antiferromagnetic ordering of the core can acquire a ma ss and show up as core excitation with "low" excitation energies around 2 m eV. [S0163-1829(99)10605-2].