Off-shell initial state effects and gauge invariance in the Drell-Yan process

Abstract

The Helicity Structure Functions in the Drell-Yan process are discussed in a framework of Parton Reggeization Approach, which includes the transverse momentum of initial-state partons in a way compatible with QED gauge-invariance. Relationships with conventional Transverse Momentum Dependent Parton Model formalism are clarified.

Comments: Proceedings of DIS-2019