An Overview of Transverse Momentum Dependent Factorization and Evolution

Abstract

I review TMD factorization and evolution theorems, with an emphasis on the treatment by Collins and originating in the Collins-Soper-Sterman (CSS) formalism. I summarize basic results while attempting to trace their development over that past several decades.Comment: 14 pages, 1 figure, Submission to EPJ A topical issue on "3D Structure of the Nucleon