Spin Puzzle in Nucleon
نویسنده
چکیده
The object of this brief review is to reconcile different points of view on how the spin of proton is made up from its constituents. On the basis of naive quark model with flavour symmetry such as isospin or SU(3) one finds a static description. On the contrary the local SU(3) colour symmetry gives a dynamical view. Both these views are contrasted and the role of U(1) axial anomaly and the ambiguity for the measurable spin content is discussed.
منابع مشابه
Generalized parton distributions, the hunt for quark orbital momenta
The Generalized Parton Distributions (GPDs) are the appropriate framework for a universal description of the partonic structure of the nucleon. They characterize the dynamics of quarks and gluons inside the nucleon and consequently contain information about the spin of the nucleon. The current experimental knowledge about GPDs is rewieved with the emphasis on the determination of Eq(Q2,x,ξ ,t),...
متن کاملep - p h / 02 09 11 5 v 2 1 7 Se p 20 02 Understanding the proton spin “ puzzle ” with a new “ minimal ” quark model
We investigate the spin structure of the nucleon in an extended Jaffe-Lipkin quark model. In addition to the conventional 3q structure, different (3q)(QQ̄) admixtures in the nucleon wavefunction are also taken into account. The contributions to the nucleon spin from various components of the nucleon wavefunction are discussed. The effect due to the Melosh-Wigner rotation is also studied. It is s...
متن کاملar X iv : h ep - p h / 02 09 11 5 v 1 1 1 Se p 20 02 Understanding the proton spin “ puzzle ” with a new “ minimal ” quark model
We investigate the spin structure of the nucleon in an extended Jaffe-Lipkin quark model. In addition to the conventional 3q structure, different (3q)(QQ̄) admixtures in the nucleon wavefunction are also taken into account. The contributions to the nucleon spin from various components of the nucleon wavefunction are discussed. The effect due to the Melosh-Wigner rotation is also studied. It is s...
متن کاملThe Nucleon Spin Crisis Bible
When the new data on polarised lepton nucleon scattering are compared at the same value of Q 2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in 0(α s), higher twist effects, modern data on unpolarised structure functions and an updated value for F/D are all important in analysing the data. The detailed x depe...
متن کاملSolving the nucleon spin puzzle based on the chiral quark soliton model
An incomparable feature of the chiral quark soliton model as compared with many other effective models like the MIT bag model is that it can give reasonable predictions not only for quark distributions but also for antiquark distributions. This will be exemplified by the argument on the positivity constraint for ū(x) + d̄(x) as well as the Soffer inequality for quark and antiquark distributions....
متن کاملar X iv : n uc l - th / 9 80 30 38 v 1 1 9 M ar 1 99 8 The A y Puzzle and the Nuclear Force
The nucleon-deuteron analyzing power A y in elastic nucleon-deuteron scattering poses a longstanding puzzle. At energies E lab below approximately 30 MeV A y cannot be described by any realistic NN force. The inclusion of existing three-nucleon forces does not improve the situation. Because of recent questions about the 3 P J NN phases, we examine whether reasonable changes in the NN force can ...
متن کامل