Volume 346 - 23rd International Spin Physics Symposium (SPIN2018) - Parallel Session: Nucleon helicity structure (F. Kunne, W. Melnitchouk and B. Page)
Theoretical predictions on polarization asymmetry for Drell-Yan process with spin- one deuteron and tensor-polarized structure function $b_1$
Q.T. Song,* S. Kumano
*corresponding author
Full text: pdf
Pre-published on: 2019 August 19
Published on: 2019 August 23
Abstract
We report recent theoretical progress on
a polarization asymmetry in the proton-deuteron Drell-Yan process
with a polarized-deuteron target and the tensor-polarized structure
function $b_1$. Experimental measurements are possible
at JLab for $b_1$ and at Fermilab for the Drell-Yan process.
First, we show a theoretical estimate for the proton-deuteron Drell-Yan
asymmetry in the Fermilab-E1039 experiment. We evolved
tensor-polarized parton distribution functions,
which explain existing HERMES $b_1$ data,
at $Q^2=2.5$ GeV$^2$ to the $Q^2$ range of the Fermilab Drell-Yan
measurements. Then, we predicted that the asymmetry is
of the order of a few percent. The Drell-Yan experiment
has an advantage to probe the tensor-polarized antiquark distributions,
which were suggested by the HERMES experiment as a finite sum for $b_1$
($\int dx b_1 (x) \ne 0$).
Second, we predicted $b_1$ for the JLab experiment by the standard
convolution model of the deuteron. Our theoretical $b_1$ structure function
seems to be much different from the HERMES data. Furthermore,
a significant distribution exists at very large $x$ ($>1$) beyond
the kinematical limit $x_{max}=1$ for the proton. Because the standard
deuteron-model estimate is much different from the HERMES data,
there could be an interesting development as a new hadron-physics field
if future JLab data will be much different from our conventional prediction.
DOI: https://doi.org/10.22323/1.346.0139
Open Access