arXiv 0710.28462007-10-15hep-ph

重夸克偶素的双光子衰变

Two-photon decay of heavy quarkonium from heavy-quark spin symmetry

T. N. Pham

备注：: 9 pages, Talk given at the QCD@Work 2007 International Workshop on QCD: Theory and Experiment}, Martina Franca, Italy, 16--20 June 2007
发表信息：: AIPConf.Proc.964:124-131,2007
DOI：: 10.1063/1.2823837

摘要：

随着最近在CLEO、Babar和Belle对$η_{c}$和$η_{c}^{\prime}$的测量，以及在Tevatron上发现$η_{b}$的前景，从基于局域算符展开和重夸克自旋对称性的有效拉格朗日量的观点来看重夸克偶素的双光子衰变似乎是合适的。在这次演讲中，我想讨论的是最近的工作，在基态和激发态的$η_c$和$η_b$使用本地运营商的扩展方法和重夸克自旋对称性，并考虑到结合能的双光子衰变率。我们发现$η_c$的双光子宽度预测值与实验值吻合较好，但$η_c(2S)$的预测值比CLEO的估计值大一倍.指出$η_b$双光子宽度与$Υ$轻子态宽度之比和$η_b $双光子宽度与模型无关，可以用来提取强耦合常数$α_s$ .

英文摘要：

With the recent measurements on $η_{c}$ and $η_{c}^{\prime}$ at CLEO, Babar and Belle, and with the prospect of finding the $η_{b}$ at the Tevatron, it seems appropriate to have another look at the two-photon decay of heavy quarkonium from the standpoint of an effective Lagrangian based on local operator expansion and heavy-quark spin symmetry. In this talk, I would like to discuss a recent work on the two-photon decay rates of ground states and excited states of $η_c$ and $η_b$ using the local operator expansion approach and heavy-quark spin symmetry and taking into account the binding-energy. We find that the predicted two-photon width for $η_c$ agrees well with experiment, but the predicted value for $η_c(2S)$ is twice larger than the CLEO estimation. We point out that the essentially model-independent ratio of $η_b$ two-photon width to the $Υ$ leptonic width and the $η_b $ two-photon width could be used to extract the strong coupling constant $α_s$ .

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英文摘要：

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