arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0905.4004hep-phhep-ex
收藏

具有次次领头阶贡献的光锥QCD求和规则中π介子的跃迁形状因子

Transition form factors of the pion in light-cone QCD sum rules with next-to-next-to-leading order contributions

S. V. Mikhailov, N. G. Stefanis

摘要:

在光锥QCD求和规则的框架下研究了π介子-光子跃迁的形状因子。计算了任何Gegenbauer谐波的下一阶阶校正的谱密度。在次-次-领先(NNLO)辐射校正的水平下,仅包括与$β$函数成比例的硬散射振幅的部分,考虑领先的零阶谐波。利用BLM尺度设置程序,分析了形状因子$F^{γ^{*}γπ}(Q^2)$预测中NNLO贡献的相对大小。此外,预测的形状因子$F^{γ^{*}ρπ}$得到原来是敏感的π介子分布振幅的端点行为,从而提供了与实验数据的π介子分布振幅的一个额外的裁决。在一个注释中添加,我们评论初步的高$Q^2$ BaBar数据$F^{γ^{*}γπ}$认为,显着增长的形状因子之间的10和40 GeV $^2$不能解释在高阶微扰修正在NNLO。

英文摘要:

The transition pion-photon form factor is studied within the framework of Light-Cone QCD Sum Rules. The spectral density for the next-to-leading order corrections is calculated for any Gegenbauer harmonic. At the level of the next-to-next-to-leading (NNLO) radiative corrections, only that part of the hard-scattering amplitude is included that is proportional to the $β$-function, taking into account the leading zeroth-order harmonic. The relative size of the NNLO contribution in the prediction for the form factor $F^{γ^{*}γπ}(Q^2)$ has been analyzed, making use of the BLM scale-setting procedure. In addition, predictions for the form factor $F^{γ^{*}ρπ}$ are obtained that turn out to be sensitive to the endpoint behavior of the pion distribution amplitude, thus providing in connection with experimental data an additional adjudicator for the pion distribution amplitude. In a note added, we comment on the preliminary high-$Q^2$ BaBar data on $F^{γ^{*}γπ}$ arguing that the significant growth of the form factor between 10 and 40 GeV$^2$ cannot be explained in terms of higher-order perturbative corrections at the NNLO.

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。

↑