Off-shell initial state effects, gauge invariance and angular distributions in the Drell–Yan process

Abstract

We discuss production of Drell–Yan lepton pairs at hadron colliders in the framework of the parton Reggeization approach, which includes off-shell initial state effects in a gauge-invariant way. Other possible prescriptions to restore gauge-invariance of hard-scattering coefficient with off-shell initial-state partons are also investigated and significant differences for the resulting structure functions are found, especially for the FUU(cos⁡2ϕ). We compare our numerical results for qT-spectra of the lepton pair with experimental data, obtained by E-288 collaboration (S=19.4 and 23.8 GeV) and find a good agreement. Also we perform predictions for the Drell–Yan structure functions at NICA pp-collider (S=24GeV). Keywords: Drell–Yan process, Angular distributions, TMD factorization, Boer–Mulders function, Gauge invariance, Parton Reggeization approach