Polarized proton-deuteron Drell-Yan processes and parton distributions

TL;DR

This paper analyzes the complex structure functions in polarized proton-deuteron Drell-Yan processes, highlighting new tensor-related functions and their potential measurement, which could advance understanding of tensor polarized antiquark distributions.

Contribution

It identifies 11 new structure functions related to the deuteron's tensor structure and discusses their measurement via Drell-Yan processes, expanding the understanding beyond proton-proton reactions.

Findings

22 finite structure functions after integration or limit

Identification of 11 new tensor-related structure functions

Potential measurement of tensor polarized antiquark distributions

Abstract

We show in general that there are 108 structure functions in the proton-deuteron Drell-Yan processes. However, there exist only 22 finite ones after integrating the cross section over the virtual-photon transverse momentum \vec Q_T or after taking the limit Q_T->0. There are 11 new structure functions in comparison with the ones of the proton-proton reactions, and they are related to the tensor structure of the deuteron. Parton-model analyses indicate an important tensor structure function V_T^{UQ_0}, which can be measured by a quadrupole spin asymmetry. The Drell-Yan process has an advantage over lepton reactions in finding tensor polarized antiquark distributions. We hope that our studies will be realized in the next-generation RHIC-Spin project and other ones.