L}$ is the turbulence mode in resonance with the CR Larmor radius. Consequently, we propose a general form for the diffusion coefficient that can account for breaks in both the high-rigidity range and the low-rigidity range (hidden in the factor $r_{\rm L}/|\delta B/B|_{k_{\rm L}}^2$ above), which reads

\[eq:def\_K\] K(R) = \_ K\_[10]{} \_ \_ \_.

In the above equation, $\beta=v/c$ is the dimensionless CR speed, and $R_{\rm l/h}$ is the location of the low/high-rigidity break, while $R_{\rm 10}$ is an intermediate rigidity (here taken at 10 GV on purpose) such that $R_{\rm l}<R_{10}<R_{\rm h}$ ($R_{\rm l}\ll R_{\rm h}$). We then get the scaling $K(R)\propto \beta^\eta R^{\delta_{\rm l}}$ in the limit $R\ll R_{\rm l}$, and the scaling $K(R)\propto R^{\delta_{\rm h}}$ in the limit $R\gg R_{\rm h}$. Therefore, $\delta_{\rm l}$, $\delta$, and $\delta_{\rm h}$ simply describe the diffusion spectral indices in the low-, intermediate-, and high-rigidity regime, respectively. The parameter $s_{\rm l}$ ($s_{\rm h}$) characterizes how fast the spectral change proceeds around $R_{\rm l}$ ($R_{\rm h}$), and is inspired by the need to describe the very smooth hardening of the B/C data showing up at high rigidity. Indeed, we recall that the previous high-rigidity analysis performed in Ref. [@GenoliniEtAl2017] provided support to 