Hunting the Gluon Orbital Angular Momentum at the Electron-Ion Collider

Xiangdong Ji, Feng Yuan, and Yong Zhao

Phys. Rev. Lett. 118, 192004 – Published 9 May 2017

Abstract

Applying the connection between the parton Wigner distribution and orbital angular momentum (OAM), we investigate the probe of the gluon OAM in hard scattering processes at the planned electron-ion collider. We show that the single longitudinal target-spin asymmetry in the hard diffractive dijet production is very sensitive to the gluon OAM distribution. The associated spin asymmetry leads to a characteristic azimuthal angular correlation of $\sin (ϕ_{q} - ϕ_{Δ})$ , where $ϕ_{Δ}$ and $ϕ_{q}$ are the azimuthal angles of the proton momentum transfer and the relative transverse momentum between the quark-antiquark pair. This study may motivate a first measurement of the gluon OAM in the proton spin sum rule.

Received 27 December 2016

DOI:https://doi.org/10.1103/PhysRevLett.118.192004

Physics Subject Headings (PhySH)

Perturbation theory Quantum chromodynamics Quark model

Nuclear PhysicsParticles & Fields

Authors & Affiliations

Xiangdong Ji^1,2, Feng Yuan³, and Yong Zhao^2,3

¹Tsung-Dao Lee Institute, and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
²Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
³Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA