Densities, Parton Distributions, and Measuring the Non-Spherical Shape of the Nucleon

Abstract

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 non-spherical shapes. We show that these matrix elements are closely related to specific transverse momentum dependent parton distributions accessible in the angular dependence of the semi-inclusive processes electron plus proton goes to electron plus pion plus anything, and the Drell-Yan reaction proton plus proton goes to a lepton anti-lepton pair plus anything. New measurements or analyses would allow the direct exhibition of the non-spherical nature of the proton.

arXiv comment7 pages, two figures

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Cited by in corpus (30)

• Transverse momentum dependent parton distributions in a light-cone quark model
• Dilepton production from polarized hadron hadron collisions
• The transverse momentum dependent distribution functions in the bag model
• Defining the Proton Radius: a Unified Treatment
• Azimuthal spin asymmetries in light-cone constituent quark models
• Transverse momentum dependent distribution functions in a covariant parton model approach with quark orbital motion
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• Rotational symmetry breaking in baby Skyrme models
• Pretzelosity TMD and Quark Orbital Angular Momentum
• Transverse structure of proton in a light-front quark-diquark model
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• Multipole decomposition of the nucleon transverse phase space
• Structure of the nucleon at leading and subleading twist in the covariant parton model
• Insights on non-perturbative aspects of TMDs from models
• Electron Structure: Shape, Size and GPDs in QED
• Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized ${}^3$He target
• Boer-Mulders effect in the unpolarized pion induced Drell-Yan process at COMPASS within TMD factorization
• Boer-Mulders function of pion meson and $q_T$-weighted $\cos 2\varphi$ asymmetry in the unpolarized ${\pi }^{-}p$ Drell-Yan at COMPASS
• Twist-4 T-even proton TMDs in the light-front quark-diquark model
• Wigner distributions for an electron
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• Spin-Orbit Correlations and Single-Spin Asymmetries
• Spontaneous Breaking of Rotational Symmetry in Rotating Solitons - a Toy Model of Excited Nucleons with High Angular Momentum
• Unraveling sub-leading twist GTMDs of proton using LFQDM
• Review of Rotational Symmetry Breaking in Baby Skyrme Models
• Deciphering Twist-3 Chiral-Even GPDs in the Light-Front Quark-Diquark Model
• Model independent results for nucleon structure
• Recent developments in nucleon spin structure with focus on h_{1L}^{\perp} and pretzelosity h_{1T}^\perp