scholarly journals On the role of quark orbital angular momentum in the proton spin

2015 ◽  
Vol 85 ◽  
pp. 02031
Author(s):  
Petr Zavada
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Proton Spin ◽  
Quark Orbital Angular Momentum

WHAT WE KNOW AND DON'T KNOW ABOUT THE ORIGIN OF THE SPIN OF THE PROTON

2010 ◽  
Vol 25 (22) ◽  
pp. 4149-4162 ◽  
Author(s):  
ANTHONY W. THOMAS ◽  
ANDREW CASEY ◽  
HRAYR H. MATEVOSYAN
Keyword(s):  
Angular Momentum ◽  
Lattice Qcd ◽  
Orbital Angular Momentum ◽  
Proton Spin ◽  
Hadron Physics ◽  
Proton Structure ◽  
Tremendous Progress ◽  
Quark Orbital Angular Momentum ◽  
Modern Information ◽  
Spin Crisis

The origin of the spin of the proton is one of the most fundamental questions in modern hadron physics. Although tremendous progress has been made since the discovery of the "spin crisis" brought the issue to the fore, much remains to be understood. We carefully review what is known and, especially in the case of lattice QCD, what is not known. We also explain the importance of QCD inspired models in providing a physical picture of proton structure and the connection between those models and what is measured experimentally and on the lattice. We specifically apply these ideas to the issue of quark orbital angular momentum in the proton. We show that the Myhrer–Thomas resolution of the proton spin crisis is remarkably consistent with modern information from lattice QCD.

scholarly journals Quark and Glue Components of the Proton Spin from Lattice Calculation

2016 ◽  
Vol 40 ◽  
pp. 1660005 ◽  
Author(s):  
Keh-Fei Liu
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Ward Identity ◽  
Proton Spin ◽  
Lattice Calculation ◽  
Quark Spin ◽  
The Status ◽  
Quark Orbital Angular Momentum ◽  
Spin Crisis ◽  
Anomalous Ward Identity

The status of lattice calculations of the quark spin, the quark orbital angular momentum, the glue angular momentum and glue spin in the nucleon is summarized. The quark spin calculation is recently carried out from the anomalous Ward identity with chiral fermions and is found to be small mainly due to the large negative anomaly term which is believed to be the source of the ‘proton spin crisis’. We also present the first calculation of the glue spin at finite nucleon momenta.

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.

scholarly journals QUARK ORBITAL ANGULAR MOMENTUM IN THE BARYON

2001 ◽  
Vol 16 (22) ◽  
pp. 3673-3697 ◽  
Author(s):  
XIAOTONG SONG
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Orbital Motion ◽  
Magnetic Moments ◽  
Sum Rule ◽  
Quark Spin ◽  
Quark Flavor ◽  
Quark Orbital Angular Momentum ◽  
Quark Flavors ◽  
Partition Factor

Analytical and numerical results, for the orbital and spin content carried by different quark flavors in the baryons, are given in the chiral quark model with symmetry breaking. The reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as a function of the partition factor κ and the chiral splitting probability a is shown. The cancellation between the spin and orbital contributions in the spin sum rule and in the baryon magnetic moments is discussed.

scholarly journals The Spin Structure of the Nucleon

2016 ◽  
Vol 40 ◽  
pp. 1660001
Author(s):  
Xiangdong Ji ◽  
Yong Zhao
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Proton Spin ◽  
Effective Theory ◽  
Large Momentum ◽  
Theory Approach ◽  
The One ◽  
The Relationship

We justify the physical meaning of the spin and orbital angular momentum of free partons in the infinite momentum frame, and discuss the relationship between the Jaffe-Manohar and Ji’s sum rules for proton spin. The parton orbital angular momentum in the Jaffe-Manohar sum rule can be measured through twist-three GPD’s in hard scattering processes such as deeply virtual Compton scattering. Furthermore, we propose that the paton orbital angular momentum as well as the gluon helicity can be calculated in lattice QCD through a large momentum effective theory approach, and provide all the one-loop matching conditions for the proton spin content in perturbative QCD.

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