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 $Q^2$.
Two Key Day-One Observables in Electron-Nucleus Collisions at the Upcoming Electron-Ion Collider and Their Implications for Baryon Number Carrier Investigations
Institute of Theoretical Physics, State Key Laboratory of Quantum Optics Technologies and Devices & Collaborative Innovation Center of Extreme Optics, Shanxi University(山西大学理论物理研究所、量子光学技术与器件国家重点实验室及极端光学协同创新中心);Laboratory of High Energy Physics, Physical-Technical Institute of Uzbekistan Academy of Sciences(乌兹别克斯坦科学院物理技术研究所高能物理实验室);Department of Natural Sciences, National University of Science and Technology MISIS (NUST MISIS), Almalyk Branch(国立科技大学米西思(NUST MISIS)阿尔马雷克分校自然科学系)
Valence quark contributions for the $γ^\ast N \to N(1440)$ form factors from Light-Front holography
本文在光阵面全息的形式下研究了核子的结构和核子的第一径向激发Roper,$N(1440)$。在价夸克自由度占优势的假设下,计算了核子弹性形状因子和$γ^\ast N \to N(1440)$跃迁形状因子。与以前的研究相反,与价夸克相关的模型的裸参数是固定的大动量转移的经验数据($Q^2$)假设的修正的三夸克图片(介子云的贡献)被抑制。然后在没有任何可调参数的情况下计算$γ^\ast N \to N(1440)$过渡形状因子。我们的估计进行了比较,从价夸克和其他模型的基础上的结果。该模型与$γ^\ast N \to N(1440)$转换形状因子的数据进行了比较,表明介子云的影响并不大,除了在$Q^2< 1.5$ GeV $^2$区域。特别是介子云对泡利形状因子的贡献很小。
所观察到的核子自旋非弹性对称性$A_{1}^{p,n}$和自旋相关的夸克分布破坏了SU(6)自旋味对称性.在夸克模型中,SU(6)对称性破缺的两种机制是众所周知的:超精细相互作用和核子的π介子云。我重新评估这些机制,并显示在每种情况下SU(6)的破缺如何影响质子的自旋相关价夸克分布。特别是我调查这些机制在运动区域$0.3 < x < 0.7$的属性,并试图测试这些对已知的数据。这两种机制都能够解释自旋不对称性的定量特征。
Constraining Proton Spin at Small $x$ with Valence Quark Model
Center of Excellence in High Energy Physics, Faculty of Science, Chulalongkorn University(朱拉隆功大学理学院高能物理卓越中心);Michigan State University(密歇根州立大学);Department of Physics, University of Jyväskylä(于韦斯屈莱大学物理系);Helsinki Institute of Physics(赫尔辛基物理研究所)
Valence quark contributions for the gamma N -> P11(1440) transition
利用协变旁观夸克模型估算了价夸克对γ N -> P11(1440)反应$F1 *(Q2)和F2*(Q2)跃迁形状因子的贡献.罗珀共振P11(1440)被假定为核子的第一径向激发。该模型不需要额外的参数,除了那些已经固定的核子的研究。计算结果与高Q2区的实验数据以及格点量子色动力学的结果一致。最后,利用该模型对CLAS和MAID分析中的介子云贡献进行了估算。
Valence quark contributions for the gamma N -> P11(1440) form factors
利用协变旁观夸克模型,我们估计了价夸克对γ N -> P11(1440)反应F1*(Q2)和F2*(Q2)跃迁形状因子的贡献.罗珀共振P11(1440)被假定为核子的第一径向激发。除了先前核子研究已经确定的参数之外,本模型不需要额外的参数。我们的结果与高Q2区的实验数据和格点量子色动力学的结果一致。我们还估计了介子云的贡献,集中在低Q2区域,预计他们将占主导地位。
Valence quark and meson cloud contributions to the $γ^\ast N \to N^\ast(1520)$ form factors
将协变旁观夸克模型应用于$γ^\ast N \to N^\ast(1520)$反应。利用大平方动量转移$Q^2$的实验数据标定了$N^\ast(1520)$波函数的协变结构,估算了价夸克对电磁形状因子和螺旋度跃迁振幅的贡献.模型结果和实验数据之间的差异,然后使用参数化的低$Q^2$的行为,介子云效应被假定为占主导地位。这种参数化对于今后的反应研究以及将过渡形状因子扩展到类时区域是非常有用的。
Valence Quark Distributions in Pions: Insights from Tsallis Entropy
South China Normal University(华南师范大学);University of Chinese Academy of Sciences(中国科学院大学);Chinese Academy of Sciences(中国科学院);Lanzhou University(兰州大学);Guizhou University of Finance and Economics(贵州财经大学)