Theoretical estimate on tensor-polarization asymmetry in proton-deuteron Drell-Yan process

Abstract

Tensor-polarized parton distribution functions are new quantities in spin-one hadrons such as the deuteron, and they could probe new quark-gluon dynamics in hadron and nuclear physics. In charged-lepton deep inelastic scattering (DIS), they are studied by the twist-two structure functions $b_1$ and $b_2$. The HERMES collaboration found unexpectedly large $b_1$ values than a naive theoretical expectation based on the standard deuteron model. The situation should be significantly improved in the near future by an approved experiment to measure $b_1$ at JLab (Thomas Jefferson National Accelerator Facility). There is also an interesting indication in the HERMES result that finite antiquark tensor polarization exists. It could play an important role in solving a mechanism on tensor structure in the quark-gluon level. The tensor-polarized antiquark distributions are not easily determined from the charged-lepton DIS; however, they can be measured in a proton-deuteron Drell-Yan process with a tensor-polarized deuteron target. In this article, we estimate the tensor-polarization asymmetry for a possible Fermilab Main-Injector experiment by using optimum tensor-polarized PDFs to explain the HERMES measurement. We find that the asymmetry is typically a few percent. If it is measured, it could probe new hadron physics, and such studies could create an interesting field of high-energy spin physics. In addition, we find that a significant tensor-polarized gluon distribution should exist due to $Q^2$ evolution, even if it were zero at a low $Q^2$ scale. The tensor-polarized gluon distribution has never been observed, so that it is an interesting future project.

10 pages, 9 eps figures, 4 style files, Phys. Rev. D in press

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Cited by in corpus (17)

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• Parton Distribution Functions of Heavy Mesons on the Light Front
• Tensor-polarized structure function $b_1$ in the standard convolution description of the deuteron
• Transverse-momentum-dependent parton distribution functions up to twist 4 for spin-1 hadrons
• Light-front holographic $\rho$-meson distributions in the momentum space
• Enhanced Tensor Polarization in Solid-State Targets
• Gluon transversity in polarized proton-deuteron Drell-Yan process
• Deuteron polarizations in the proton-deuteron Drell-Yan process for finding the gluon transversity
• Equation-of-motion and Lorentz-invariance relations for tensor-polarized parton distribution functions of spin-1 hadrons
• Parton distribution functions and fragmentation functions of spin-1 hadrons
• Semi-inclusive deep inelastic scattering off a tensor-polarized spin-1 target
• Tensor-polarized twist-3 parton distribution functions $f_{LT}(x)$ for the spin-1 deuteron by using twist-2 relations
• Estimate on Spin Asymmetry for Drell-Yan Process at Fermilab with Tensor-Polarized Deuteron
• TMDs for spin-1 hadrons
• Twist-3 contribution in the Drell-Yan process with tensor-polarized deuteron
• Twist-2 relation and sum rule for tensor-polarized parton distribution functions of spin-1 hadrons
• Standard convolution description of deuteron tensor spin structure