Rapidity divergences and valid definitions of parton densities

Abstract

Rapidity divergences occur when parton densities in a gauge theory are defined in the most natural way, as expectation values of partonic number operators in light-front quantization. I review these and other related divergences, and show how the definitions of parton densities can be modified to remove the divergences. A modified definition is not only essential for many phenomenological applications of QCD, but also concerns the treatment of parton densities in non-perturbative approaches. The necessity of modifications in the definition of a parton density also entails corrections in the formulation of light-front quantization for gauge theories.

9 pages. To appear in Proceedings of LIGHT CONE 2008

References in corpus (1)

• Renormalization, Wilson lines, and transverse-momentum dependent parton distribution functions

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