Statistical Quark Model for the Nucleon Structure Function

The European Physical Journal C, 2008

Within a statistical model of linear confined quarks we obtain the flavor asymmetry and corresponding structure function of the nucleon. The model parameters are fixed by the experimental available data. The temperature parameter is adjusted by the Gottfried sum rule violation and the chemical potentials by the corresponding up (u) and down (d) quark normalizations in the nucleon. The light antiquark and quark distributions in the proton, given by d/u, d/u and d − u, as well as the neutron to proton ratio of the structure functions, extracted from the experimental data, are well fitted by the model. As the quarkconfining strengths should be flavor dependent, a mechanism is introduced in the model to adjust the corresponding distribution, in order to improve the comparison obtained for the sea-quark asymmetries in the nucleon with the available experimental analysis.

AIP Conference Proceedings, 2010

We consider some existingrelativistic modelsfor thenucleon structurefunctions,relying on statistical approaches instead of perturbative ones. Thesem odels areb ased on theF ermi-Dirac distributionf or thec onfinedq uarks, whereadensity of energy levels is obtainedf roma ne ffective confining potential. In this context, it is presenteds ome results obtainedw ith ar ecents tatistical quark modelf or thes ea-quark asymmetry in then ucleon. It is shown, within this model,t hat experimental availableo bservables,s ucha st he ratio andd ifferenceb etween proton andn eutron structuref unctions,a re quite well reproduced with just threep arameters: twoc hemical potentials used to reproducethe valenceupand down quark numbers in thenucleon, andatemperature that is beingusedtor eproducethe Gottfried sumruleviolation.

European Physical Journal C, 1999

The strangeness content of the nucleon is determined from a statistical model using confined quark levels, and is shown to have a good agreement with the corresponding values extracted from experimental data. The quark levels are generated in a Dirac equation that uses a linear confining potential (scalar plus vector). With the requirement that the result for the Gottfried sum rule violation, given by the New Muon Collaboration (NMC), is well reproduced, we also obtain the difference between the structure functions of the proton and neutron, and the corresponding sea quark contributions.

Nuclear Physics B - Proceedings Supplements, 2010

Effective Quark mass shift, gluonic and pionic effects EFFECTIVE LIGHT QUARK MASS SHIFT The difference between the interaction of u and d quarks is supposed to come from instanton effects, which are flavour-spin dependent [Dorokhov et al, Sov.J.Part.Nucl. 23 (1992) 522].

Nuclear Physics A, 2007

A statistical model of linear-confined quarks is applied to obtain the flavor asymmetry of the nucleon sea. The model parametrization is fixed by the experimental available data, where a temperature parameter is used to fit the Gottfried sum rule violation. Results are presented for the ratios of light quark and antiquark distributions, d/u andd/ū. * Our thanks to the Brazilian funding agencies FAPESP and CNPq for partial support. Nuclear Physics A 790 (2007) 522c-525c 0375-9474/$ -see front matter

Phys. Rev. C 108, 035203, 2023

In this study, we performed calculations and analyses of the structure functions of polarized nucleons and light nuclei, specifically 3 He and 3 H, using second-order Feynman diagrams. Our investigation focused on two main aspects: First, we examined the symmetry properties of polarized light sea quarks. Second, we conducted a detailed investigation into the impacts of symmetry breaking on the structure functions of both nucleons and nuclei. To achieve this, we utilized the existing polarized parton distribution functions (polarized PDFs) available in the literature. These PDFs were used to calculate and compare the polarized structure functions g 1 and g 2 of the nuclei. Additionally, we examined and analyzed the Bjorken and Efremov-Leader-Teryaev sum rules by utilizing the moments of the polarized structure functions. The Lorentz color force components, namely F y,n E and F y,n B , were determined using the twist-2, twist-3, and twist-4 matrix elements. When symmetry breaking is applied, it is observed that they have similar magnitudes but opposite signs. Our theoretical predictions for the polarized structure functions of nucleons and light nuclei, taking into account the symmetry breaking of light sea quarks, exhibit better agreement with experimental data.

Physics Letters B, 1982

Journal of Physics: Conference Series, 2016

A simple statistical model is developed with the Fock states being the mesonhadron fluctuations. As expected, a insight about the violation of the Gottfried sum rule is obtained, and also a small difference between the strangeness amount in proton and neutron is explained.

AIP Conference Proceedings, 2005

We have developed a physical model for the non-perturbative x-shape of parton density functions in the proton, based on Gaussian fluctuations in momenta, and quantum fluctuations of the proton into meson-baryon pairs. The model describes the proton structure function and gives a natural explanation of observed quark asymmetries, such as the difference between the anti-up and anti-down sea quark distributions and between the up and down valence distributions. We also find an asymmetry in the momentum distribution of strange and anti-strange quarks in the nucleon, large enough to reduce the NuTeV anomaly to a level which does not give a significant indication of physics beyond the standard model.

A physical model for parton densities in hadrons, based on Gaussian momentum fluctuations of partons and hadronic baryon-meson fluctuations, is presented. The model has previously been shown to describe proton structure function data, and is now applied to sea quark asymmetries and shown to describe the dbar-ubar asymmetry of the proton. By considering fluctuations involving strange quarks, the model gives an asymmetry between the momentum distributions of s and sbar, which would reduce the significance of the NuTeV anomaly.