2003/04/30 by Xiangdong Ji · 4 citations
Physics and Astronomy · #Gluon #High-Energy Particle Collisions Research #Light cone #Momentum (technical analysis) #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Parton #Phase space #Physics #Position and momentum space #Proton #Proton spin crisis #Quantum #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Quark #Space (punctuation) #Spin (aerodynamics) #Wigner distribution function #hep-ph
paper · pdf · doi:10.1103/physrevlett.91.062001
published as Phys.Rev.Lett. 91 (2003) 062001 · 4 pages
arxiv created 2003/06/18 · openalex publication_date 2003/08/07 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
While the form factors and parton distributions provide separately the shape of the proton in coordinate and momentum spaces, a more powerful imaging of the proton structure can be obtained through phase-space distributions. Here we introduce the Wigner-type quark and gluon distributions which depict a full-3D proton at every fixed light-cone momentum, like what is seen through momentum ("color") filters. After appropriate phase-space reductions, the Wigner distributions are related to the generalized parton distributions (GPDs) and transverse-momentum dependent parton distributions, which are measurable in high-energy experiments. The new interpretation of GPDs provides a classical way to visualize the orbital motion of the quarks, which is known to be the key to the spin and magnetic moment of the proton.