Speaker
Description
SpinQuest is a polarized fixed-target Drell-Yan experiment at Fermi National Accelerator Laboratory, utilizing a 120 GeV proton beam incident upon transversely polarized NH$_3$ and ND$_3$ targets. The primary goal of the experiment is the determination of the $\bar{u}$ and $\bar{d}$ contribution to a single-spin azimuthal asymmetry in the production of virtual photons in the invariant mass range $4<M<8$ GeV. This asymmetry, called the Sivers asymmetry, arises from a spin-momentum correlation between the transverse momentum $\vec{k}_T$ of a parton and the spin axis $\vec{S}$ of the nucleon. A non-zero $\bar{u}$ and/or $\bar{d}$ Sivers asymmetry implies a non-zero orbital angular momentum of the $\bar{u}$ and/or $\bar{d}$ quarks. Non-zero Sivers asymmetries have already been observed for valence quarks in leptonic deep-inelastic scattering at HERMES and COMPASS. In addition to this fundamental measurement in nucleon spin physics, we will also observe the transverse single-spin asymmetry in the production of $J/\psi$ particles, which is sensitive to the gluon Sivers function. Additionally, observing a sign change in the light quark sea Sivers asymmetry between this measurement and future deep-inelastic measurements at the Electron-Ion Collider would be a test of a fundamental prediction of Quantum Chromodynamics. In this presentation I will review the physics and technology underpinning the experiment.
