2007/08/16 by Gerald A. Miller · 2 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevc.76.065209
published as Phys.Rev.C76:065209,2007 · 7 pages, two figures
arxiv created 2007/08/16 · openalex publication_date 2007/12/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Spin-dependent quark densities, matrix elements of specific density operators in proton states of definite spin-polarization, indicate that the nucleon may harbor an infinite variety of nonspherical shapes. We show that these matrix elements are closely related to specific transverse-momentum-dependent (TMD) parton distributions accessible in the angular dependence of the semi-inclusive processes ep\ensuremath→e\ensuremathπX and the Drell-Yan reaction pp\ensuremath→llX. New measurements or analyses would allow the direct exhibition of the nonspherical nature of the proton.