  We compute the sphaleron rate on the lattice. We adopt a novel strategy based
on the extraction of the spectral density via a modified version of the
Backus-Gilbert method from finite-lattice-spacing and finite-smoothing-radius
Euclidean topological charge density correlators. The physical sphaleron rate
is computed by performing controlled continuum limit and zero-smoothing
extrapolations both in pure gauge and, for the first time, in full QCD.
