The sphaleron rate in SU(N) gauge theory

The sphaleron rate is defined as the diffusion constant for topological number N-CS equivalent to integral g(2)F (F) over tilde /32 pi(2). It establishes the rate of equilibration of axial light quark number in QCD and is of interest both in electroweak baryogenesis and possibly in heavy ion collisions. We calculate the weak-coupling behavior of the SU(3) sphaleron rate, as well as making the most sensible extrapolation towards intermediate coupling which we can. We also study the behavior of the sphaleron rate at weak coupling at large N-c.