Spin Structure Functions of the Nucleon (original) (raw)
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The (spin) structure of the nucleon
The European Physical Journal A - Hadrons and Nuclei, 2003
Within the framework of the quark-parton model and perturbative QCD the spin-dependent structure functions of the nucleon are discussed. The formalism suggests dramatic behavior for the distribution describing the polarization of the d quark in a polarized proton (or a u quark in a polarized neutron), Possible experimental tests of this result are noted.
The spin structure of the nucleon: A phenomenological introduction
Progress in Particle and Nuclear Physics, 2012
The investigation of the spin structure of the nucleon via semi-inclusive deep inelastic scattering on polarized nucleons is updated with the most recent results of the JLab, HERMES, and COMPASS experiments. A short description is given of these experiments, which are complementary in phase space and use sophisticated and different techniques to polarize the nucleon targets. The cases of target spin parallel or orthogonal to the direction of the incoming lepton require different experimental techniques, have a different phenomenology and need a different theoretical treatment. After reviewing these differences, the most recent transverse spin advances are presented, and evidence is given that the new data already allow for a rather precise extraction of the transversity and of the Sivers PDFs.
Within the framework of the quark-parton model and perturbative QCD the spin-dependent structure functions of the nucleon are discussed. The formalism suggests dramatic behavior for the distribution describing the polarization of the d quark in a polarized proton (or a u quark in a polarized neutron), Possible experimental tests of this result are noted.
Recent results on the spin structure of the nucleon
Czechoslovak Journal of Physics, 1999
FOrt THE HERMES COLLABOrtATmN The process of polarised deep inelastic scattering and the information it has given on the spin structure of the nucleon are introduced. The experimental programmes in this field are described and the latest inclusive and semi-inclusive data and analyses are reviewed. Proposed future measurements are summarised. 1.
New insights into the spin structure of the nucleon
Physical Review D, 2013
We analyze the low-energy spin structure of the nucleon in a covariant effective field theory with explicit spin-3/2 degrees of freedom to third order in the small scale expansion. Using the available data on the strong and electromagnetic width of the ∆-resonance, we give parameter-free predictions for various spin-polarizabilities and moments of spin structure functions. We find an improved description of the nucleon spin structure at finite photon virtualities for some observables and point out the necessity of a fourth order calculation.
The “Spin” Structure of the Nucleon — a Lattice Investigation
International Journal of Modern Physics C
We will discuss here an indirect lattice evaluation of the baryon axial singlet current matrix element. This quantity may be related to the fraction of nucleon spin carried by the quarks. The appropriate structure function has recently been measured (EMC experiment). As in this experiment, we find that the quarks do not appear to carry a large component of the nucleon spin.
The Angular Momentum Structure of the Nucleon
AIP Conference Proceedings, 2008
The proton spin budget is discussed. Results are presented from inclusive and semiinclusive deep inelastic scattering and from deeply virtual Compton scattering. They permit interpretations towards the determination of various contributions to the proton spin.
Nucleon and nuclear spin structure functions
arXiv: Nuclear Theory, 1997
Nuclear effects in polarized inelastic electron scattering off polarized 3He^3He3He and polarized 2H^2H2H are discussed; in the resonance region, Fermi motion effects are found to be much larger than in deep inelastic scattering. It is shown that improperly describing nuclear dynamics would lead to the extraction of unreliable neutron spin structure functions; on the other hand side, simple and workable equations, relating the Gerasimov -- Drell -- Hearn Integral for the neutron to the corresponding quantity for 3He^3He3He and 2H^2H2H, are proposed. Nuclear effects in the recent E143 data are estimated by a proper procedure.
Exploring the transverse spin structure of the nucleon
AIP Conference Proceedings, 2008
We discuss our present understanding of the transverse spin structure of the nucleon and of related properties originating from parton transverse motion. Starting from the transversity distribution and the ways to access it, we then address the role played by spin and transverse momentum dependent (TMD) distributions in azimuthal and transverse single spin asymmetries. The latest extractions of the Sivers, Collins and transversity functions are also presented.
The Longitudinal Spin Structure of the Nucleon
2000
We are proposing a comprehensive program to map out the x-and Q 2 -dependence of the helicity structure of the nucleon in the region of moderate to very large x where presently the experimental uncertainties are still large. The experiment will use the upgraded CLAS12 detector, 11 GeV highly polarized electron beam, and longitudinally polarized solid ammonia targets (NH 3 and ND 3 ). Thanks to the large acceptance of CLAS12, we will cover a large kinematical region simultaneously. We will detect both the scattered electrons and leading hadrons from the hadronization of the struck quark, allowing us to gain information on its flavor. Using both inclusive and semi-inclusive data, we will separate the contribution from up and down valence and sea quarks in the region 0.1 ≤ x ≤ 0.8. These results will unambiguously test various models of the helicity structure of the nucleon as x → 1. A combined Next-to-Leading Order (NLO) pQCD analysis of our expected data together with the existing world data will significantly improve our knowledge of all polarized parton distribution functions, including for the gluons (through Q 2 -evolution). High statistics data on the deuteron in the region of moderate x and with a fairly large range in Q 2 are crucial for this purpose. Finally, we will be able to improve significantly the precision of various moments of spin structure functions at moderate Q 2 , which will allow us to study duality and higher-twist contributions.