Instead, one general result that has been found is the following:
because the pitch-angle cosine, μ, is confined to μ ∈ [−1, 1],
pitch-angle scattering as based on Eqs (2b) and (3) is not a process
that can be described for asymptotically long times. Instead,
the proper time has to be found where (i) Dμμ is no longer dominated
by the initial conditions; but (ii) Dμμ is not yet dominated
by the 1/t dependence because Δμ cannot grow any further.
However, with the additional constraint that the turbulence
strength is not too high, there always seems to be a time period
where excellent agreement with the analytical results can
be obtained.