Effect of symmetry breaking of polarized light sea quarks on the nucleon and nuclear structure functions, and sum rules

Abstract

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: Firstly, we examined the symmetry properties of polarized light sea quarks. Secondly, 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 $F_E^{y,n}$ and $F_B^{y,n}$, are 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.