Rigidity dependence of the parallel and perpendicular mean free path, as inferred by the inverse solutions listed in Tables 2 and 3. The green triangles and magenta squares correspond to electrons and protons, respectively. The area denoted by the dashed gray line corresponds to the Palmer consensus. The other dashed curves depict the empirical relation suggested by Dröge (2000) (purple), the analytical approximations of Teufel & Schlickeiser (2002, 2003) for electrons under damping turbulence (DT) and random sweeping (RS) (green and cyan, respectively); the corresponding relation for protons under both DT and RS is also depicted (violet).