Related papers: Constituent Quarks and g_1
The proton spin crisis still remains an unsolved problem in particle physics. It is suggested in the literature that the gauge invariant spin and orbital angular momentum of the quark and the gauge invariant total angular momentum of the…
Effect of the quark intrinsic motion on the proton spin structure functions is demonstrated. It is shown, that the covariant version of the quark-parton model taking into account the orbital motion gives the consistent picture of the proton…
The nucleons (protons and neutrons) are by far the most abundant form of matter in our visible Universe; they are composite particles made of quarks and gluons, the fundamental quanta of Quantum Chromo Dynamics (QCD). The usual…
Our knowledge of the nucleon spin structure has greatly improved over the last twenty years or so, but still many fundamental questions remain unsolved. I will try to review some of the puzzling aspects of the structure of the nucleon spin,…
Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon. Our approach consists of the two main steps. At…
The present status of the nucleon's spin structure is reviewed with emphasis on new experimental results.
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…
Understanding the spin structure of the proton is one of the main challenges in hadronic physics. While the concepts of spin and orbital angular momentum are pretty clear in the context of non-relativistic quantum mechanics, the…
I calculate the quark contributions to the axial and tensor charges and the spin structure of the proton. The result indicates that the valence current quark spins carry 1/3 of the proton spin, the total contribution of quark spins to the…
The real, interacting elementary particle always consits of a 'bare' particle and a cloud of virtual particles mediating a self-interaction and/or the bond inside a composite object. In this letter we discuss the question of spin content of…
A brief summary of the theoretical and experimental knowledge of the spin structure of the proton is presented. The helicity distributions of quark and gluons are discussed, together with their related sum rules. The transversity…
The leading chiral contributions to the quark and gluon components of the proton spin are calculated using heavy-baryon chiral perturbation theory. Similar calculations are done for the moments of the generalized parton distributions…
We review some aspects of spin physics where QCD instantons play an important role. In particular, their large contributions in semi-inclusive deep-inelastic scattering and polarized proton on proton scattering. We also review their…
We briefly review some of the recent developments in QCD spin physics.
We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the…
We investigate the relation between the topology of a nucleon and its spin composition. We approach this question in (1+1) dimensional single-flavor QCD with a large number of color. In this limit the theory can be shown to be dual to the…
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…
We review some of the recent developments in QCD spin physics and highlight the spin program now underway at RHIC.
We derive the consequences of the Myhrer-Thomas explanation of the proton spin problem for the distribution of orbital angular momentum on the valence and sea quarks. After QCD evolution these results are found to be in very good agreement…
We review what is currently known about the transverse spin structure of hadrons, in particular from observables that can be analyzed within a collinear framework. These effects have been around for 40 years and represent a critical test of…