Fig. 2: Comparison to diffusion theory.
a Error of the least squares of the fit of Eq. (1), in the absence of SAL ((kl) → ∞), to the data with R and ℓ as adjustable parameters (triangles). In the frequency range marked with red and blue full circles, we find R = 0.66 ± 0.05 or z0 ≃ 3.25 ± 0.5, both in the higher and lower frequency branch (inset). Full circles: results from least-squares fitting when setting R = 0.66 constant. b Far from the gap, for \({\nu }^{\prime}\ne [0.383,0.535]\), transport is diffusive and all data for T(L/ℓ) can be collapsed on a master curve given by Eq. (1) (yellow line) with \(\tilde{L}=L\) and z0 = 3.25(R = 0.66). Red (blue) full circles refer to the same data at frequencies lower (higher) than \({\nu }_{{\rm{Gap}}}^{\prime}\) shown in (a). Data for L < 2.7a, not taken into account for the fitting procedure, are marked with gray symbols.
