  The topology of configuration space may be responsible in part for the
existence of sphalerons. Here, sphalerons are defined to be static but unstable
finite-energy solutions of the classical field equations. Another manifestation
of the nontrivial topology of configuration space is the phenomenon of spectral
flow for the eigenvalues of the Dirac Hamiltonian. The spectral flow, in turn,
is related to the possible existence of anomalies. In this review, the
interconnection of these topics is illustrated for three particular sphalerons
of SU(2) Yang-Mills-Higgs theory.
