arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0910.3077hep-ph
收藏

非局部凝聚下QCD求和规则和局部对偶方法中的π介子形状因子

Pion Form Factor in QCD Sum Rules with Nonlocal Condensates and in the Local-Duality Approach

Alexander P. Bakulev, A. V. Pimikov, N. G. Stefanis

摘要:

讨论了在$O(α_s)$近似下计算类空电磁π介子形状因子的QCD求和规则方法。我们发现,凝聚体的非局部性是一个关键点,包括非微扰贡献的π形状因子。我们比较我们的结果与本地的对偶预测,并表明连续阈值$s_0(Q^2)$参数是高度低估的本地的对偶方法在$Q^2\gtrsim 2$ GeV $^2$。使用我们适合这个参数,$s_0^\text{LD}(Q^2)$,并应用分数解析微扰理论,我们估计的精度为1%的顺序的$O(α_s^2)$贡献的π介子的形状因子。

英文摘要:

We discuss the QCD sum-rule approach for the spacelike electromagnetic pion form factor in the $O(α_s)$ approximation. We show that the nonlocality of the condensates is a key point to include nonperturbative contributions to the pion form factor. We compare our results with the Local-Duality predictions and show that the continuum threshold $s_0(Q^2)$ parameter is highly underestimated in the Local-Duality approach at $Q^2\gtrsim 2$ GeV$^2$. Using our fit for this parameter, $s_0^\text{LD}(Q^2)$, and applying the fractional analytic perturbation theory, we estimate with an accuracy of the order of 1% the $O(α_s^2)$ contribution to the pion's form factor.

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。

↑