Abstract
The polarized strange quark puzzle concerns the fact that the polarized strange quark density extracted from polarized inclusive deep inelastic scattering data is significantly negative, whereas it is zero or slightly positive when extracted from a combined analysis of polarized semi-inclusive and inclusive deep inelastic data. SU(3) flavor symmetry, which, it is generally accepted, is not an exact symmetry, plays an important role in the inclusive analysis, and all the extracted polarized quark densities depend, to some extent, on the level of symmetry breaking introduced. But by far the most sensitive to the breaking is the strange quark density. In this paper we present a NLO QCD analysis of the world data on polarized inclusive DIS data on protons, neutrons and deuterons, including the final JLAB CLAS/EG1b data on the proton and deuteron, and study the sensitivity of the strange quark polarization to the breaking of flavor SU(3).
Highlights
Our knowledge of the internal partonic spin structure of the nucleon comes mainly from the polarized inclusive and semi-inclusive deep inelastic scattering (DIS) of leptons on nucleons
There is a growing precision of the measurements of magnetic moments, gA=gV ratios and rates in hyperon β decays, and different theoretical models ([12] and more recently [13]) have been used to study how large any flavor SUð3Þ symmetry breaking should be in order to describe well these new data, and how big could be the deviation of a8 from its SUð3Þ symmetric value
In order to study the effects on the polarized PDFs on the deviation of a8 from its SUð3Þ symmetric value, we have performed the following fits: (a) Fit A: The data is fitted using the SUð3Þ symmetric value 0.586 for a8 (7). (b) Fit B: The data is fitted using a8 1⁄4 0.46. This value corresponds to the maximal reduction of a8 presented in the literature and is the value predicted in one of the models on SUð3Þ-breaking effects [13]
Summary
Our knowledge of the internal partonic spin structure of the nucleon comes mainly from the polarized inclusive and semi-inclusive deep inelastic scattering (DIS) of leptons on nucleons. There is a growing precision of the measurements of magnetic moments, gA=gV ratios and rates in hyperon β decays, and different theoretical models ([12] and more recently [13]) have been used to study how large any flavor SUð3Þ symmetry breaking should be in order to describe well these new data, and how big could be the deviation of a8 from its SUð3Þ symmetric value In this connection we would like to mention the QCD analysis [14] of the polarized inclusive DIS data, where for the uncertainty of the SUð3Þ symmetry value of a8 has been used a value approximately six times bigger than that obtained from the phenomenological analysis of the data on hyperon β decays. Note here that in contrast to the light sea quark densities, the total strange quark density ðΔs þ ΔsÞðx; Q2Þ can be well determined from the inclusive data if they are sufficiently precise [18]
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