Electroweak Baryogenesis from a Classical Force

We describe a new effect that produces baryons at a first order electroweak phase transition. It operates when there is a CP-violating field present on propagating bubble walls. The novel aspect is that it involves a purely classical force, which alters the motion of particles across the wall and through diffusion creates a chiral asymmetry in front of the wall. We develop a technique for computing the baryon asymmetry using the Boltzmann equation, and a fluid approximation which allows us to model strong scattering effects. The final formula for the baryon asymmetry has a remarkably simple form.