用小$x$价夸克模型约束质子自旋
Constraining Proton Spin at Small $x$ with Valence Quark Model
AI总结：
本文利用价夸克模型结合螺旋度演化方程，通过全局分析极化DIS数据，以更少参数显著降低质子自旋预测不确定性，并发现小x处正胶子hPDF与负g1结构函数。
AI中文摘要：
最近，一项全局分析针对极化深度非弹性散射（DIS）过程中的纵向自旋不对称性展开，将极化价夸克模型与大$N_c \& N_f$螺旋度演化方程相结合。与先前基于玻恩近似的传统中等$x$模型分析相比，价夸克模型将自由参数数量减少了三倍，并使得质子内总部分子自旋的预测不确定性降低了六倍。基于价夸克模型的拟合预测在小$x$处存在正的胶子螺旋度部分子分布函数（hPDF）和负的$g_1$结构函数。然而，拟合中$\u03c7^2$统计量的增加值得进一步审视价夸克模型的物理不确定性，相关工作正在进行中。本文末尾还总结了其他可能的未来研究方向。
英文摘要：
Recently, a global analysis has been performed for longitudinal spin asymmetries in polarized deep inelastic scattering (DIS) processes, combining the polarized valence quark model with the large-$N_c \& N_f$ helicity evolution equations. With a three-fold reduction in the number of free parameters, the valence quark model results in a six-fold reduction of uncertainty for the resulting prediction of total parton spin inside the proton, when compared to previous analysis performed with traditional moderate-$x$ model inspired by Born approximation. The fit based on valence quark model predicts a positive gluon hPDF and negative $g_1$ structure function at small $x$. However, the resulting increase in the $χ^2$-statistic of the fit warrants further examination into the physical uncertainty of the valence quark model, which is a work in progress. We also summarize other possibilities of future research directions towards the end of this article.
