A ${\bf Z}_2$ Origin for B+L Violation in the Hot Electroweak Theory
Minos Axenides, Andrei Johansen, HOLGER BECH NIELSEN, Ola Törnkvist · arXiv (Cornell University) · 1995
The space of static finite-energy configurations of the electroweak theory admits a ${\bf Z}_{2}$ topological structure. Odd-parity configurations with odd pure-gauge behavior at spatial infinity (S sphaleron, W-Z strings, multisphalerons) mediate rapid $B+L$ violation in the Early Universe. Configurations with even pure-gauge behavior (S$^{*}$ sphalerons, W-Z strings, multisphalerons) are trivial and topologically equivalent to the vacuum.