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arXiv 2407.05923hep-ph
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奇特强子中价夸克分布的最大熵方法:对 $Z_c(3900)$ 案例的研究

Maximum Entropy Method for Valence Quark Distributions in Exotic Hadrons: A Study of the $Z_c(3900)$ Case

Chengdong Han, Xiaopeng Wang, Wei Kou, Xurong Chen

AI总结:

本文利用最大熵方法研究奇特强子价夸克分布,发现峰值随价夸克数增加向小 $x$ 移动,并估计 $Z_c(3900)$ 初始半径为 $r_c=1.276$ fm,同时提出其电荷形状因子可由基于广义分布振幅的 QCD 计数规则截面提取。

摘要:

在本研究中,我们展示了应用最大熵方法(Maximum Entropy Method,MEM)来确定奇特强子的价夸克分布。我们的研究得到三个关键发现。首先,我们观察到,随着价夸克数目的增加,强子价夸克分布的峰值位置显著向更小的 Bjorken 标度 $x$ 移动,这与 Kawamura 和 Kumano 先前的结果一致。其次,假设 $Z_c(3900)$ 最初由四个价夸克组成,我们采用 MEM 确定其初始价夸克分布,并在极低分辨率标度 $Q^2$ 下估计其半径为 $r_c=1.276$ fm。此外,我们发现我们在领头阶计算得到的电荷形状因子 $G_c(q)$ 与强子分子态计算的结果之间存在显著差异。我们提出,该形状因子可以从 QCD 计数规则截面中提取,而该截面基于与多夸克态相联系的广义分布振幅(Generalized Distribution Amplitudes,GDA)。

英文摘要:

In this study we demonstrate the application of the Maximum Entropy Method (MEM) to determine the valence quark distribution of exotic hadrons. Our investigation yields three key findings. Firstly, we observe a significant shift towards smaller Bjorken scale $x$ in the peak position of the valence quark distribution for hadrons with an increasing number of valence quarks, consistent with previous results by Kawamura and Kumano. Secondly, assuming that the $Z_c(3900)$ initially consists of four valence quarks, we employ MEM to determine its initial valence quark distribution, estimating a radius of $r_c=1.276$ fm at an extremely low resolution scale $Q^2$. Furthermore, we identify a notable discrepancy between our computed charge form factor $G_c(q)$ at leading order and the outcomes of hadron molecular state calculations. We propose that this form factor can be extracted from the QCD counting rule cross-section, which is grounded in Generalized Distribution Amplitudes (GDA) linked to the multi-quark states.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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