Electromagnetic form factors of the pion and kaon from the instanton vacuum
Electromagnetic form factors of the pion and kaon from the instanton vacuum
复制标题
DOI：
10.1103/physrevd.77.094014
复制
发表时间：
2007-09
影响因子：
5
通讯作者：
S. Nam;Hyun-Chul Kim
中科院分区：
文献类型：
--
作者：
S. Nam;Hyun-Chul Kim
我们基于在大 Nc 极限下测量的瞬时真空的低能有效手性作用，研究了类空间区域中的 π 介子和 kaon ( + , K + , K 0 ) 电磁形状因子：Q 2 < 1 GeV。考虑了显式的 SU(3) 对称性破缺。事实证明，非局部贡献对于重现实验数据至关重要。虽然 π 介子电磁形状因子与数据非常吻合，但 kaon 电磁形状因子似乎被低估了。我们还计算了π介子和Kaon的电磁电荷半径：hr 2 i + = 0:455 fm 2 、hr 2 iK+ = 0:534 fm 2 和hr 2 iK0 = 0:060 fm 2 ，除了平均瞬子尺寸和瞬子间距离外，没有任何可调整的自由参数，并且它们与实验数据兼容。大 Nc 极限下的低能常数 L9 估计为 8:42 10 3
We investigate the pion and kaon ( + , K + , K 0 ) electromagnetic form factors in the space-like region: Q 2 < 1 GeV, based on the gauged low-energy eective chiral action from the instanton vacuum in the large Nc limit. Explicit avor SU(3) symmetry breaking is taken into account. The nonlocal contributions turn out to be crucial to reproduce the experimental data. While the pion electromagnetic form factor is in good agreement with the data, the kaon one seems underestimated. We also calculate the electromagnetic charge radii for the pion and kaon: hr 2 i + = 0:455 fm 2 , hr 2 iK+ = 0:534 fm 2 andhr 2 iK0 = 0:060 fm 2 without any adjustable free parameter except for the average instanton size and inter-instanton distance, and they are compatible with the experimental data. The low-energy constant L9 in the large Nc limit is estimated to be 8:42 10 3 from the