FERMION SEA ALONG THE SPHALERON BARRIER

We study the fermion Dirac sea along the minimal energy path between t opologically distinct vacua in the electroweak theory. We follow in de tail the interplay between the bound state and the continuum in the fe rmion creation and/or annihilation, as one passes from one vacuum to a nother. We calculate the quantum correction to the classical energy of the sphaleron barrier, arising from the fermion sea, and its contribu tion to the baryon number violation rate for nonzero temperatures. We find that the fermion fluctuations suppress that rate if the mass of t he top quark is large enough.