Related papers: Do gluons carry half of the nucleon momentum?
We estimate in the QCD sum rule approach the amount of the nucleon spin carried by the gluon angular momentum: the sum of the gluon spin and orbital angular momenta. The result indicates that gluons contribute at least one half of the…
~Based on the gauge invariant quark canonical momentum we construct two theoretically possible decompositions of nucleon momentum to those of quarks and gluons. We predict that either 6% or 21% of nucleon momentum is carried by gluons,…
In the past few years, a lot of evidences have been accumulated, which indicate that the gluon polarization inside the nucleon is likely to be small at least at the low renormalization scales. On the other hand, the recent lattice QCD…
The fundamental program in high energy spin physics focuses on the spin structure of the nucleon. The gluon and orbital angular momentum components of the nucleon spin are virtually unknown. The J_z=1/2 sum rule involves the integrated…
Determination of the orbital angular momentum of the proton is a difficult but important part of understanding fundamental structure. Insight can be gained from suitable models of the gluon asymmetry applied to the Jz = 1/2 sum rule. We…
Considerable progress has been made in our knowledge of the spin distribution within the proton. The recently measured limits on polarized gluons in the proton suggest polarized gluons contribute very modestly to the proton spin. We will…
Since the announcement of the proton spin crisis by the European Muon Collaboration there has been considerable progress in unravelling the distribution of spin and orbital angular momentum within the proton. We review the current status of…
The orbital angular momentum is one of the least understood of the spin characteristics of a proton. There are no direct ways to model the orbital angular momentum. However, the Jz=1/2 sum rule includes an angular momentum component and can…
We affirm that the proper momentum defined in [PRL 103:062001 (2009)] does respect exact gauge symmetry and is as measurable as the kinetic momentum. The physical part of the gauge field is also as measurable as the electromagnetic field.…
This talk consists of four parts. In part one, I give an elementary discussion on constructing a Lorentz-invariant spin sum rule for the nucleon. In part two, I discuss a gauge-dependent spin sum rule, explore its relation with the…
In analogy to the Altarelli-Parisi equation for the quark and gluon helicity contributions to the nucleon spin, we derive an evolution equation for the quark and gluon orbital angular momenta. The solution of the combined equations yields…
The twenty years since the announcement of the proton spin crisis by the European Muon Collaboration has seen tremendous progress in our knowledge of the distribution of spin within the proton. The problem is reviewed, beginning with the…
About half the mass of a hadron is given from gluonic contributions. In this talk we calculate the chromo-electric and chromo-magnetic components of the nucleon mass. These computations are numerically difficult due to gluon field…
In the context of the so-called valon model, we calculate $\frac{\delta g}{g}$ and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of…
It is well known that in gauge theories, the spin (and orbital angular momentum) of gauge particles is not gauge invariant, although the helicity is; neither are the canonical momentum and canonical angular momentum of charged particles.…
It is shown that the amplitude for the scattering of a heavy quarkonium system from a nucleon near threshold is completely determined by the fraction of angular momentum, as well as linear momentum, carried by gluons in the nucleon. A form…
We have calculated the Orbital Angular Momentum of quarks and gluons in the nucleon. The calculations are carried out in the next to leading order utilizing the so-called valon model. It is found that the average quark orbital angular…
We discuss the impact of recent high-statistics RHIC data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find clear evidence for a non-vanishing…
The authors claim to have found a "proper", "gauge-invariant" definition of a charged-particle's momentum in gauge theory, which is more "superior" than the textbook version. I show that their result arises from a misunderstanding of gauge…
In this paper, we use momentum sum rule to compute the fractions of momentum carried by quarks and gluons in a self-similarity based model of proton. Comparison of the results with the prediction of QCD asymptotics is also made.