arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.12902hep-phhep-exnucl-th
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强子中价夸克分布的一个新特征

A Novel Feature of Valence Quark Distributions in Hadrons

Christopher Leon, Misak M. Sargsian, Frank Vera

摘要:

考察了用Bjorken x加权的价夸克分布最大值$h(x,t)\equiv xq_V(x,t)$的演化,我们发现在峰处的$h(x,t)$应该变成一个单参数函数:$h(x_p,t)=Φ(x_p(t))$,其中$x_p$是峰的位置,而$t= \log{Q^2}$ .利用这一观测结果导出了一个新的模型无关关系,它通过$x_p$-函数$Φ(x_p(t))$的对数的导数将$x_p$中的价部分子分布函数(PDF)的偏导数与QCD演化方程联系起来.使用经验PDF的这种关系的数值分析导致观察到$Φ(x_p(t)) = h(x_p,t) = Ce^{D x_p(t)}$的指数形式,用于导致覆盖四个数量级的所有$Q^2$范围的PDF的下一个到下一个前导阶近似。观测到的“高度-位置”相关函数的指数$D$随着近似阶数的增加而收敛。这一结果适用于所有考虑的PDF集。一个类似的关系也观察到的π价夸克分布,表明所获得的关系可能是普遍的任何非单线态部分子分布。观察到的“高度-位置”关联也被用来表明,没有有限的数交换可以描述的峰的位置处的价夸克分布在固定的$Q^2$的分析行为。

英文摘要:

Examining the evolution of the maximum of valence quark distribution weighted by Bjorken x, $h(x,t)\equiv xq_V(x,t)$, we observe that $h(x,t)$ at the peak should become a one parameter function; $h(x_p,t)=Φ(x_p(t))$, where $x_p$ is the position of the peak and $t= \log{Q^2}$. This observation is used to derive a new model independent relation which connects the partial derivative of the valence parton distribution functions (PDFs) in $x_p$ to the QCD evolution equation through the $x_p$-derivative of the logarithm of the function $Φ(x_p(t))$. A numerical analysis of this relation using empirical PDFs results in a observation of the exponential form of the $Φ(x_p(t)) = h(x_p,t) = Ce^{D x_p(t)}$ for leading to next-to-next leading order approximations of PDFs for the all $Q^2$ range covering four orders in magnitude. The exponent, $D$, of the observed "height-position" correlation function converges with the increase of the order of approximation. This result holds for all PDF sets considered. A similar relation is observed also for pion valence quark distribution, indicating that the obtained relation may be universal for any non-singlet partonic distribution. The observed "height - position" correlation is used also to indicate that no finite number exchanges can describe the analytic behavior of the valence quark distribution at the position of the peak at fixed $Q^2$.

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