CSS Equation, etc, Follow from Structure of TMD Factorization

Understand

I show that the forms of the Collins-Soper-Sterman and renormalization-group equations for the evolution of transverse-momentum-dependent (TMD) parton densities in QCD follow from the structure of TMD factorization.

• A derivation does not need to directly use detailed properties of the operator definition of the TMD parton densities.