Spin asymmetry for proton-deuteron Drell-Yan process with tensor-polarized deuteron

Abstract

Tensor structure of the deuteron can be studied by deep inelastic scattering and Drell-Yan process to understand it in terms of quark and gluon degrees of freedom. It probes interesting features in the deuteron including a D-wave contribution. In the charged-lepton DIS, twist-two structure functions $b_1$ and $b_2$ are expressed by tensor-polarized parton distribution functions (PDFs). We note that the HERMES experimental measurement of $b_1$ seems to be much different from a conventional theoretical prediction. This puzzling situation should be significantly improved in the near future by an approved experiment to measure $b_1$ at JLab. On the other hand, the tensor-polarized PDFs, especially antiquark distributions, could be measured by spin asymmetries in the Drell-Yan process with a tensor-polarized deuteron at Fermilab. In this work, we estimate tensor-polarization asymmetries for the Fermilab Drell-Yan experiment by using a parametrization for the tensor-polarized PDFs to explain the HERMES $b_1$ data. Obtained spin asymmetries are typically a few percent order and they could be measured by the Fermilab-E1039 experiment. Since the tensor-polarized antiquark distributions will play an important role to solve the puzzle, further theoretical and experimental efforts are needed toward the Drell-Yan experiment at Fermilab and other hadron facilities.