标题： 手征求和规则对于${\cal L}^{WZ}_{(6)}$参数及在$π^0,η,η'$衰变中的应用 显示英文标题

标题： Chiral Sum-Rules for ${\cal L}^{WZ}_{(6)}$ Parameters and Application to $π^0,η,η'$ Decays

摘要： 手征展开的低能过程 $\pi^0\to\gamma\gamma$ 和 $\eta\to\gamma\gamma$ 被重新考虑，特别强调从 ${\cal L}^{WZ}_{(6)}$ 中评估两个低能参数的问题，这些参数在手征顺序六中出现。展示了如何广泛使用求和规则和用共振饱和以及来自渐近 QCD 的约束来有效确定它们的值。给出了夸克质量比 $m_s/{\hat m}$的标准和非标准值的宽度预测。建立了通常现象学的 $\eta-\eta'$混合参数与手征展开参数之间的精确关系。可以基于一个简单的计数规则来理解对 $\eta$衰变的手征修正的大小：$O(1/N_c)\sim\ O(m_q)$。 它展示了如何最终使这一计数规则能够以一致和系统的方式将$\eta'$包含到有效拉格朗日量中。 显示英文摘要

摘要： The chiral expansion of the low energy processes $\pi^0\to\gamma\gamma$ and $\eta\to\gamma\gamma$ is reconsidered with particular emphasis on the question of the evaluation of the two low-energy parameters from ${\cal L}^{WZ}_{(6)}$ which are involved at chiral order six. It is shown how extensive use of sum-rules and saturation with resonances as well as constraints from asymptotic QCD effectively determine their values. Predictions for the widths are presented for both standard and non-standard values of the quark mass ratio $m_s/{\hat m}$. A precise relation is established between the usual phenomenological $\eta-\eta'$ mixing parameters and those of the chiral expansion. The large size of the chiral correction to the $\eta$ decay can be understood on the basis of a simple counting rule: $O(1/N_c)\sim\ O(m_q)$. It is shown how this counting rule eventually allows one to include the $\eta'$ into the effective lagrangian in a consistent and systematic way.