Related papers: Quark spin in the proton
A review of the calculations of the proton's spin using lattice QCD is presented. Results for the three contributions, the quark contribution $\sum_{q=u,d,s,c} (\frac{1}{2} {\Delta q})$, the total angular momentum of the quarks $J_q$ and of…
We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our…
The problem of our understanding of the spin structure of the nucleon has been with us since the publication of the EMC measurements of the polarised structure function of the proton in 1987. In this talk a review of the results presented…
The spin structure of the system of quasifree fermions having total angular momentum $J=1/2$ is studied in a consistently covariant approach. Within this model the relations between the spin functions are obtained. Their particular cases…
The proton is one of the main building blocks of all visible matter in the universe. Among its intrinsic properties are its electric charge, mass, and spin. These emerge from the complex dynamics of its fundamental constituents, quarks and…
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 this work, we examine the impact of QCD phase transitions on the quark spin fluctuations and correlations. We propose the quark-antiquark correlation, which relates to the vector meson spin alignment and the $\Lambda-\bar\Lambda$…
I review recent developments in theoretical spin physics. Topics include pion production in nucleon-nucleon collisions, the implications of heavy quark spin symmetry for heavy hadron molecules, the nucleon electric dipole form factors and…
I describe a few of the most exciting open questions in high energy spin physics. After a brief look at (g-2)_\mu and the muon electric dipole moment, I concentrate on QCD spin physics. Pressing questions include the interpretation of new…
Gluon topology makes a potentially important contribution to the spin of the constituent quark.
The chiral quark model describes the strangeness components of the light quarks as fluctuations into strange mesons and quarks. The single strange pseudoscalar and vector meson loop fluctuations of the constituent $u$- and $d$-quarks give…
For a long time people made the mistake of thinking the proton was understood. New experiments, ranging from form factors to deeply virtual Compton scattering, promise a new era of highly informative studies. Among the controversial topics…
In light of recent experimental progress in determining the pressure and shear distributions in the proton, these quantities are calculated in a model with confined quarks supplemented by the pion field required by chiral symmetry. The…
A unique feature of quantum chromodynamics (QCD), the theory of strong interactions, is the possibility for gluonic degrees of freedom to participate in the construction of physical hadrons, which are color singlets, in an analogous manner…
A whole class of non-perturbative QCD studies, e.g. the instanton models, chiral quark models, etc. indicates that the effective degrees of freedom for the physics in the low Q^(2) < 1 GeV^(2) region could be the constituent quarks (CQs)…
In the infinite mass limit for a heavy quark its spin decouples from the QCD dynamics, which leads to the heavy-quark spin symmetry. After a short discussion of spin symmetry some applications are considered.
It is shown that, based only upon two empirically known facts besides two reasonable theoretical postulates, we are inevitably led to a model-independent conclusion that the quark orbital angular momentum carries nearly half of the total…
Recent progress from Jefferson Lab has significantly improved our understanding of the nucleon spin structure in the high-$x$ region. Results from two experiments in Hall A are presented. The first experiment is a precision measurement of…
This article gives an overview over recent results on quark and gluon helicity distributions obtained in deep inelastic lepton nucleon scattering and proton proton interactions. Future experimental programs to study the nucleon structure…
We briefly summarize the important and critical roles that PHENIX Experiment has played in determining the proton's internal structure in terms of quarks and gluons, and their dynamics. Some pioneering measurements by PHENIX Experiment on…