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arXiv 0809.1744hep-phhep-lat
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手征夸克模型中π介子的引力和高阶形状因子

Gravitational and higher-order form factors of the pion in chiral quark models

Wojciech Broniowski, Enrique Ruiz Arriola

摘要:

在两种手征夸克模型中计算了π介子的引力形状因子,并与最近的全QCD格点数据进行了比较。我们发现很好的协议的情况下,光谱夸克模型,建立在矢量介子占主导地位的电荷形状因子。我们推导出引力和电磁形状因子之间的一个简单的关系,在考虑夸克模型手征极限。这个关系意味着引力的均方半径是电磁半径的一半。我们还分析了高阶夸克广义形状因子的π介子,有关的对称Bjorken X变量的广义部分子分布函数的高阶矩,并讨论其微扰QCD演化,需要将夸克模型预测的晶格数据。在晶格上计算的t=0时的高阶夸克形状因子的值在统计和方法不确定性范围内也与我们的夸克模型结果一致。

英文摘要:

The gravitational form factor of the pion is evaluated in two chiral quark models and confronted to the recent full-QCD lattice data. We find good agreement for the case of the Spectral Quark Model, which builds in the vector-meson dominance for the charge form factor. We derive a simple relation between the gravitational and electromagnetic form factors, holding in the considered quark models in the chiral limit. The relation implies that the gravitational mean squared radius is half the electromagnetic one. We also analyze higher-order quark generalized form factors of the pion, related to higher moments in the symmetric Bjorken X-variable of the generalized parton distribution functions, and discuss their perturbative QCD evolution, needed to relate the quark-model predictions to the lattice data. The values of the higher-order quark form factors at t=0, computed on the lattice, also agree with our quark model results within the statistical and method uncertainties.

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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