  I discuss 3 related quantities: the cusp anomalous dimension, the HQET
heavy-quark field anomalous dimension, and the quark-antiquark potential.
Leading large $n_f$ terms can be calculated to all orders in $\alpha_s$. Next
to leading terms with the abelian color structure $C_F^2$ also can be found to
all orders (but not non-abelian $C_F C_A$ terms). This talk is based on
Appendices C and D in [arXiv:1510.07803].
