Understanding the evolution of transverse-momentum dependent parton densities

Abstract

Different approaches to define transverse-momentum dependent parton distribution functions are considered from the point of view of their renormalization-group properties. The associated one-loop anomalous dimensions of these quantities are presented and compared to each other. We give arguments in favor of the "pure light-like" definition, and the use of the light-cone gauge.

Comments: 4 pages. Talk presented by the first author at Workshop on the International Workshop "Transverse Partonic Structure of Hadrons", 21-26 Jun 2009, Erevan, Armenia