Calculation of the diffusion constant of muons in metals at low temperatures

The diffusion constant of muons in metals at low temperatures is derived from the muon Boltzmann equation under the assumption that electron-muon scattering dominates, and a T^-1 behaviour is obtained. This temperature dependence compares favorably with the experimental result that the diffusion constant is proportional to T^-0.6 for positive muons in aluminium. However, the calculated absolute value of the diffusion constant around 1K is still in severe disagreement with experiment.