论文标题
$πη$相互作用和$ a_0 $ ressonances in Photon-Photon散射
The $πη$ interaction and $a_0$ resonances in photon-photon scattering
论文作者
论文摘要
我们重新查看有关两个最轻的$ a_0 $共振和$ s $ - 波$πη$散射的信息，这些散射可以从光子 - 光子散射实验中提取。为此，我们为满足分析性能，两通道单位性并遵守软光子以及软质旋转约束的$ s $波光子光子振幅构建了一个模型。基本的I = 1 Hadronic $ t $ -matrix涉及六个现象学参数，并且能够说明低于1.5 GEV的两个共振。我们的$γγ\ to toπη$和$γγ\ y和$γγ\ to k_sk_s $ high Statistical from belle belle协作的总拟合。发现$χ^2 $的最小化具有两个不同的解决方案，其解决方案大约等于$χ^2 $。其中一种表现出轻巧而狭窄的激发$ A_0 $共振，类似于Belle分析中的共振。但是，这需要$ j = 0 $和$ j = 2 $共振效果之间的特殊重点，这很可能是非物理的。在这两种解决方案中，$ A_0（980）$共振出现在第二个Riemann纸上。该极点在物理解决方案中的位置确定为$ m-iγ/2 = 1000.7^{+12.9} _ { - 0.7} -i \，36.6^{+12.7} _ { - 2.6} $ MEV。还将溶液与衰减$η\toπ^0γγ$的运动区域的实验数据进行了比较。在该区域中，必须添加与$π^+π^ - $撤销相关的差异贡献，我们必须为我们提供分散评估。
We revisit the information on the two lightest $a_0$ resonances and $S$-wave $πη$ scattering that can be extracted from photon-photon scattering experiments. For this purpose we construct a model for the $S$-wave photon-photon amplitudes which satisfies analyticity properties, two-channel unitarity and obeys the soft photon as well as the soft pion constraints. The underlying I=1 hadronic $T$-matrix involves six phenomenological parameters and is able to account for two resonances below 1.5 GeV.We perform a combined fit of the $γγ\to πη$ and $γγ\to K_SK_S$ high statistics experimental data from the Belle collaboration. Minimisation of the $χ^2$ is found to have two distinct solutions with approximately equal $χ^2$. One of these exhibits a light and narrow excited $a_0$ resonance analogous to the one found in the Belle analysis. This however requires a peculiar coincidence between the $J=0$ and $J=2$ resonance effects which is likely to be unphysical. In both solutions the $a_0(980)$ resonance appears as a pole on the second Riemann sheet. The location of this pole in the physical solution is determined to be $m-iΓ/2=1000.7^{+12.9}_{-0.7} -i\,36.6^{+12.7}_{-2.6}$ MeV. The solutions are also compared to experimental data in the kinematical region of the decay $η\toπ^0γγ$. In this region an isospin violating contribution associated with $π^+π^-$ rescattering must be added for which we provide a dispersive evaluation.
