Orbital angular momentum, spin fractions, and scenarios for the proton's spin-weighted parton distributions

1989 ◽  
Vol 39 (1) ◽  
pp. 361-364 ◽  
Author(s):  
Gordon P. Ramsey ◽  
Jian-Wei Qiu ◽  
David Richards ◽  
Dennis Sivers
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Parton Distributions

QUARK ORBITAL ANGULAR MOMENTUM AND GENERALIZED PARTON DISTRIBUTIONS

2003 ◽  
Vol 18 (08) ◽  
pp. 1303-1309 ◽  
Author(s):  
XIANGDONG JI
Keyword(s):  
Angular Momentum ◽  
Quantum Chromodynamics ◽  
Orbital Angular Momentum ◽  
Parton Distributions ◽  
Generalized Parton Distributions ◽  
Quark Orbital Angular Momentum

In this talk, I review the merit of introducing and measuring the quark orbital angular momentum contribution to the spin of the nucleon in the context of quantum chromodynamics.

Generalized TMDs

2015 ◽  
Vol 37 ◽  
pp. 1560037 ◽  
Author(s):  
Koichi Kanazawa ◽  
Cedric Lorcé ◽  
Andreas Metz ◽  
Barbara Pasquini ◽  
Marc Schlegel
Keyword(s):  
Angular Momentum ◽  
Transverse Momentum ◽  
Perturbative Qcd ◽  
Orbital Angular Momentum ◽  
Close Relation ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Model Independent ◽  
Mere Existence

Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. In this contribution, which is largely based on a recent publication,1 we focus on two twist-2 GTMDs which are denoted by F1,4 and G1,1 in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of F1,4 and G1,1 has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the GTMDs in two spectator models and in perturbative QCD. For the model results we also explicitly check the relation to the orbital angular momentum of partons inside hadrons.

GPDs AND TMDs

2012 ◽  
Vol 20 ◽  
pp. 75-83
Author(s):  
MATTHIAS BURKARDT
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Transverse Plane ◽  
Final State ◽  
Parton Distributions ◽  
Generalized Parton Distributions ◽  
Wigner Distributions ◽  
Quark Orbital Angular Momentum ◽  
Final State Interactions ◽  
The Difference

For transversely polarized nucleons the distribution of quarks in the transverse plane is transversely shifted and that shift can be described in terms of Generalized Parton Distributions (GPDs). This observation provides a 'partonic' derivation of the Ji-relation for the quark angular momentum in terms of GPDs. Wigner distributions are used to show that the difference between the Jaffe-Manohar definiton of quark orbital angular momentum and that of Ji is equal to the change of orbital angular momentum due to the final state interactions as the struck quark leaves the target in a DIS experiment.

scholarly journals Quark Spin-Orbit Correlations

2015 ◽  
Vol 37 ◽  
pp. 1560036 ◽  
Author(s):  
Cédric Lorcé
Keyword(s):  
Angular Momentum ◽  
Phase Space ◽  
Orbital Angular Momentum ◽  
Valence Quark ◽  
Complete Characterization ◽  
Proton Spin ◽  
Spin Orbit ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Quark Spin

The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.

scholarly journals WIGNER DISTRIBUTIONS AND QUARK ORBITAL ANGULAR MOMENTUM

2012 ◽  
Vol 20 ◽  
pp. 84-91 ◽  
Author(s):  
CÉDRIC LORCÉ ◽  
BARBARA PASQUINI
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Constituent Quark ◽  
Constituent Quark Model ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Generalized Parton Distributions ◽  
Wigner Distributions ◽  
Quark Orbital Angular Momentum ◽  
Quark Phase

We discuss the quark phase-space or Wigner distributions of the nucleon which combine in a single picture all the information contained in the generalized parton distributions and the transverse-momentum dependent parton distributions. In particular, we present results for the distribution of unpolarized quarks in a longitudinally polarized nucleon obtained in a light-front constituent quark model. We show how the quark orbital angular momentum can be extracted from the Wigner distributions and compare it with alternative definitions.

scholarly journals SPIN AND OTHER ASPECTS OF GENERALIZED PARTON DISTRIBUTIONS

2003 ◽  
Vol 18 (08) ◽  
pp. 1319-1326
Author(s):  
MARKUS DIEHL
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Parton Distribution ◽  
Bound States ◽  
Quantum Mechanical ◽  
Longitudinal Structure ◽  
Parton Distributions ◽  
Generalized Parton Distributions ◽  
Mechanical Interference ◽  
Higher Spin

I discuss how generalized parton distribution probe various aspects of QCD bound states. Topics include the interplay between transverse and longitudinal structure, quantum mechanical interference, orbital angular momentum, helicity flip, and higher-spin targets.

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