Non-Abelian Dipole Radiation and the Heavy Quark Expansion

Dipole radiation in QCD is derived to the second order in αₛ. A powerlike evolution of the spin-singlet heavy quark operators is obtained to the same accuracy. We give an O(αₛ²) relation between the short-distance low-scale running heavy quark mass and the mass in the modified minimal subtraction scheme. We discuss the properties of an effective QCD coupling αₛ⁽ᵈ⁾(E) which governs the dipole radiation. We argue that this coupling is advantageous for describing heavy quark physics.