Constraints on the Light Pseudoscalar Meson Distribution Amplitudes from Their Meson-Photon Transition Form Factors
Constraints on the Light Pseudoscalar Meson Distribution Amplitudes from Their Meson-Photon Transition Form Factors
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DOI：
10.1103/physrevd.84.074011
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发表时间：
2011-06
影响因子：
5
通讯作者：
Xing-Gang Wu;Tao Huang
中科院分区：
文献类型：
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作者：
Xing-Gang Wu;Tao Huang
介子-光子跃迁形状因子{伽马}{伽马}*{产额}P(P代表{pi}，{eta}和{eta}‘)对伪标量介子的分布幅度提供了很强的约束。本文在光锥微扰QCD方法下，同时考虑了价夸克和非价夸克的贡献，计算了这些跃迁形式因子。为了保持一致性，采用统一的波函数模型对这些形状因子进行了分析。结果表明，在合适的魅力分量f{sup{eta}‘{sup c}{约x}-30 MeV和中等的DA(约为0.30)的情况下，可以同时解释整个q{sup 2}区的Q{sup 2}F{sub{eta}{Gamma}}(Q{sup 2})和Q{sup 2}F{sub{eta}’{Gamma}}(Q{sup 2})的实验数据。此外，还详细讨论了组分夸克质量m{subQ}和m{subS}、参数B、混合角{Phi}和f{sub{eta}‘}{supc}所引起的形状因子的不确定性。结果发现，在合理的范围内调整这些参数，可以在一定程度上改善形状因子，但不能解决Q{sup 2}F{Sub{pi}{Gamma}}(Q{sup 2})的难题，特别是不能一致地解释整个Q{sup 2}区域内{pi}-{Gamma}形状因子的行为。我们希望在大的Q{sup 2}区域中关于这些形式更多的因子的进一步的实验数据能够澄清目前的情况。
The meson-photon transition form factors {gamma}{gamma}*{yields}P (P stands for {pi}, {eta} and {eta}') provide strong constraints on the distribution amplitudes of the pseudoscalar mesons. In this paper, these transition form factors are calculated under the light-cone perturbative QCD approach, in which both the valence and nonvalence quarks' contributions have been taken into consideration. To be consistent, a unified wave function model is adopted to analyze these form factors. It is shown that with the proper charm component f{sub {eta}}'{sup c}{approx}-30 MeV and a moderate DA with B{approx}0.30, the experimental data on Q{sup 2}F{sub {eta}{gamma}}(Q{sup 2}) and Q{sup 2}F{sub {eta}'{gamma}}(Q{sup 2}) in the whole Q{sup 2} region can be explained simultaneously. Furthermore, a detailed discussion on the form factors' uncertainties caused by the constituent quark masses m{sub q} and m{sub s}, the parameter B, the mixing angle {phi}, and f{sub {eta}'}{sup c} are presented. It is found that, by adjusting these parameters within their reasonable regions, one can improve the form factor to a certain degree but cannot solve the puzzle for Q{sup 2}F{sub {pi}{gamma}}(Q{sup 2}), especially to explain the behavior of the {pi}-{gamma} form factor within the whole Q{sup 2} region consistently. We hope further experimental data on these formmore » factors in the large Q{sup 2} region can clarify the present situation.« less