Gauge-invariant TMD factorization for Drell-Yan Helicity Structure Functions

In framework of the Parton Reggeization Approach, we obtain gauge invariant hadronic tensor W μν for Drell-Yan process in Transverse Momentum Dependent factorization. We show that use of Fadin-Sherman effective vertex, which describes annihilation of Reggeized quark-antiquark into virtual photon, leads to new relations between Helicity Structure Functions F U U ( 1 , 2 cos ϕ , c o s 2 ϕ ) and Parton Distribution Functions ( f 1 q ( x , q T ) , h 1 ⊥ q ( x , q T ) ) in unpolarized proton-proton collisions. We estimate numerically relative contributions of parton number density function f 1 q ( x , q T ) and Boer-Mulders function h 1 ⊥ q ( x , q T ) in the Helicity Structure Functions F U U ( 1 ) and F U U ( cos 2 ϕ ) at the kinematical conditions of the future collider NICA.