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arXiv 1504.02844hep-phhep-exnucl-th
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同位旋破缺衰变$η(1405) \to f_0(980)π^0 \to 3π$

Isospin breaking decay $η(1405) \to f_0(980)π^0 \to 3π$

N. N. Achasov, A. A. Kozhevnikov, G. N. Shestakov

备注：
10 pages, 8 figures. Added are the details of calculations, 2 references, and clarifying remarks
发表信息：
Phys. Rev. D 92, 036003 (2015)
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摘要：

在文献中，有人试图通过包含对数（三角形）奇异性的机制，即，从理论上解释衰变$η(1405)$ \，$\to$\，$f_0(980)π^0$ \，$\to$ \，$ 3π$中同位素不变性的大破坏，是由于转换$η(1405)\to(K^*\bar K+\bar K^*K)\to(K^+K^-+K^0\bar K^0)π^0\to f_0(980)π^0\to3π$。对稳定$K^*$介子的假设情况进行了相应的计算。在这里，我们表明，帐户的有限宽度的$K^*$（$Γ_{K^*\to Kπ}\approx50$兆电子伏）平滑的对数奇点的振幅和结果的抑制计算的衰减宽度$η(1405)\to f_0(980) π^0\to3π$的因素$6-8$相比，$Γ_{K^*\to Kπ}$ \，=\，0。我们还分析了与假设的优势的$η(1405)\to(K^*\bar K+\bar K^*K)\to K\bar Kπ$衰变机制的困难，并讨论了可能的动力学的衰变$η(1405)\toηππ$。在共振结构$η(1405/1475)$衰变为$K\bar Kπ$和$ηππ$的过程中，$K\bar K$、$ Kπ$、$ηπ$和$ππ$质谱的实验数据以及在$K\bar Kπ$和$ηππ$衰变通道中共振峰本身的形状的决定性改进对于进一步建立$η(1405)\to3 π$衰变机制是必要的。

英文摘要：

There are attempts in the literature to theoretically explain the large breaking of isotopic invariance in the decay $η(1405)$\,$\to$\,$f_0(980)π^0$\,$\to$\,$ 3π$ by the mechanism containing the logarithmic (triangle) singularity, i.e., as being due to the transition $η(1405)\to(K^*\bar K+\bar K^*K)\to(K^+K^-+K^0\bar K^0)π^0\to f_0(980)π^0\to3π$. The corresponding calculations were fulfilled for a hypothetic case of the stable $K^*$ meson. Here, we show that the account of the finite width of the $K^*$ ($Γ_{K^*\to Kπ}\approx50$ MeV) smoothes the logarithmic singularities in the amplitude and results in the suppression of the calculated decay width $η(1405)\to f_0(980) π^0\to3π$ by the factor of $6-8$ as compared with the case of $Γ_{K^*\to Kπ}$\,=\,0. We also analyze the difficulties related with the assumption of the dominance of the $η(1405)\to(K^*\bar K+\bar K^*K)\to K\bar Kπ$ decay mechanism and discuss the possible dynamics of the decay $η(1405)\toηππ$. The decisive improvement of the experimental data on the $K\bar K$, $ Kπ$, $ηπ$, and $ππ$ mass spectra in the decay of the resonance structure $η(1405/1475)$ to $K\bar Kπ$ and $ηππ$, and on the shape of the resonance peaks themselves in the $K\bar Kπ$ and $ηππ$ decay channels is necessary for the further establishing the $η(1405)\to3 π$ decay mechanism.

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。

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