Diffusion flux, ℱ_L, predicted by the degenerate Landau Eq. (26)for the razor-thin quasi-Keplerian disc introduced in Sect. 2.2. Following the convention from Eq. (26), the direction of diffusion of individual wires in action space is given by −ℱ_L. Red contours, for which ℱ_L< 0, correspond to regions where wires tend to diffuse towards larger L, that is decrease their eccentricity. Blue contours, for which ℱ_L> 0, are associated with regions in action space, where individual wires tend to diffuse towards smaller L, that is increase their eccentricity. The contours are spaced linearly between the minimum and the maximum of ℱ_L. Within the units of Eq. (6), the maximum value for the positive blue contours is given by , while the minimum value for the negative red contours reads .