Hard-scattering factorization with heavy quarks: A general treatment

A detailed proof of hard-scattering factorization is given with the inclusion of heavy quark masses. Although the proof is explicitly given for deep-inelastic scattering, the methods apply more generally. The power-suppressed corrections to the factorization formula are uniformly suppressed by a power of Λ/Q, independently of the size of heavy quark masses, $M,$ relative to $Q.$