A nonperturbative measurement of the broken phase sphaleron rate

We develop a method to compute the sphaleron rate in the electroweak broken phase nonperturbatively. The rate is somewhat slower than a perturbative estimate. In SU(2)×U(1) Higgs theory at the physical value of ΘW, and assuming that the latent heat of the phase transition reheats the universe to the equilibrium temperature, baryon number erasure after the phase transition is prevented only when (λ/g2)≤0.036.