Dimensionless diffusion coefficient ﹩{d}_{\mathrm{RR}}﹩ (Equation (23)) as a function of j at different SMAs. At small eccentricity (﹩1-j\ll 1﹩), ﹩{d}_{\mathrm{RR}}﹩ can be approximated by ﹩{d}_{\mathrm{RR}}\approx \langle {\tau }_{\parallel }^{2}\rangle /{\tilde{\tau }}^{2}\approx 0.07(1-j)﹩ (dashed line). When the relativistic precession approaches ﹩\sim 0.45/{T}_{{\rm{c}}}﹩, ﹩{d}_{\mathrm{RR}}﹩ drops as j becomes an adiabatic invariant. The cusp’s parameters are the same as in Figure 1.