arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1004.0837hep-ph
收藏

用Regge方法计算π介子跃迁形状因子和不完全矢量介子优势

Pion transition form factor in the Regge approach and incomplete vector-meson dominance

Enrique Ruiz Arriola, Wojciech Broniowski

摘要:

不完全矢量介子优势的概念和Regge模型被应用到π介子的跃迁形状因子。首先,我们认为,手征夸克模型的变体履行手征异常可能会违反寺泽-韦斯特幺正性界限,因为这些界限是基于未经验证的假设的振幅的实部,排除了可能存在的多项式项。一个直接的结果是,跃迁形状因子不一定在光子虚性的大值处消失。此外,在BaBar实验的范围内,寺泽-韦斯特界限比数据高出一个数量级,因此是形式上的而不是实际的兴趣。然后,我们展示了如何在一个简单的模型与一个国家,以及在更复杂的Regge模型的实验数据可能会得到适当的解释与不完全矢量介子的优势。简单的Regge模型沿着Dominguez线的推广导致数据的正确描述,其中可以以满足或违反Terazawa-West界限的方式调整参数。我们还从Z -> pi 0 γ衰变中施加了实验约束。最后指出光子动量不对称性参数对分析精度的影响。

英文摘要:

The concept of incomplete vector-meson dominance and Regge models is applied to the transition form factor of the pion. First, we argue that variants of the chiral quark model fulfilling the chiral anomaly may violate the Terazawa-West unitarity bounds, as these bounds are based on unverified assumptions for the real parts of the amplitudes, precluding a possible presence of polynomial terms. A direct consequence is that the transition form factor need not necessarily vanish at large values of the photon virtuality. Moreover, in the range of the BaBar experiment, the Terazawa-West bound is an order of magnitude above the data, thus is of formal rather than practical interest. Then we demonstrate how the experimental data may be properly explained with incomplete vector-meson dominance in a simple model with one state, as well as in more sophisticated Regge models. Generalizations of the simple Regge model along the lines of Dominguez result in a proper description of the data, where one may adjust the parameters in such a way that the Terazawa-West bound is satisfied or violated. We also impose the experimental constraint from the Z -> pi0 gamma decay. Finally, we point out that the photon momentum asymmetry parameter may noticeably influence the precision analysis.

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。

↑