Topological Classification of Odd-Parity Sphaleron Deformations

We discuss topological aspects of the electroweak sphaleron and its odd-parity deformations. We demonstrate that they are uniquely classified in terms of their odd and even-parity pure gauge field behaviour at spatial infinity. Fermion level crossing occurs only for odd-parity configurations which are topologically disconnected from the vacuum. They contribute to the high temperature unsuppressed baryon violating thermal transitions. Deformations with even-parity pure gauge behaviour at spatial infinity are topologically trivial and do not mediate baryon number violation in the early Universe.