  The baryon number is violated in the Standard Model by non-perturbative
sphaleron transitions. At temperatures above the electroweak scale, the rate of
the sphaleron transitions is unsuppressed and has been accurately measured
using effective theories on the lattice. At temperatures substantially below
the electroweak scale, the Higgs field expectation value is large and the
sphaleron rate is strongly suppressed. Here analytical estimates are
sufficient. The sphaleron rate, however, has not been calculated in the
intermediate temperature range with physical Standard Model parameters. In this
work we use an effective electroweak theory on the lattice with multicanonical
and real-time simulation methods to calculate the sphaleron rate through the
electroweak crossover at Higgs masses of 115 GeV and 160 GeV. The results are
significant e.g. for Leptogenesis scenarios.
