arXiv 1001.32902010-01-19hep-ph

重子光谱学与质量起源

Baryon Spectroscopy and the Origin of Mass

Eberhard Klempt

备注：: Hadron 2009 invited talk, 8 pages, 6 figures, 4 tables
DOI：: 10.1063/1.3483358

摘要：

质子质量来自于手征对称性的自发破缺和组分夸克的形成。它们的动力学不能用质子断层扫描来检验，而只能通过研究激发态重子来检验。然而，激发态重子的数量比夸克模型中预期的要少得多;更糟糕的是，许多已知态的存在在最近的一项分析中受到了挑战，与旧的分析相比，该分析包括来自介子工厂的高精度数据。因此，$πN$弹性散射数据并不能为重子激发谱的任何唯象分析提供一个有充分根据的起点。光生实验现在开始填补这个漏洞。通常，它们会证实旧的发现，甚至提出一些新的状态。这些结果鼓励人们尝试将观察到的重子共振模式与夸克模型的预测进行比较，从介子-核子散射振幅动态生成重子的模型，从基于引力理论的模型，并与手征对称性可能在高激发能下恢复的猜想进行比较。最好的协议被发现与一个简单的质量公式内AdS/QCD。我们的理解QCD的后果进行了讨论，以及实验，这可能有助于决定模型的有效性。

英文摘要：

The proton mass arises from spontaneous breaking of chiral symmetry and the formation of constituent quarks. Their dynamics cannot be tested by proton tomography but only by studying excited baryons. However, the number of excited baryons is much smaller than expected within quark models; even worse, the existence of many known states has been challenged in a recent analysis which includes - compared to older analyses - high-precision data from meson factories. Hence $πN$ elastic scattering data do not provide a well-founded starting point of any phenomenological analysis of the baryon excitation spectrum. Photoproduction experiments now start to fill in this hole. Often, they confirm the old findings and even suggest a few new states. These results encourage attempts to compare the pattern of observed baryon resonances with predictions from quark models, from models generating baryons dynamically from meson-nucleon scattering amplitudes, from models based on gravitational theories, and with the conjecture that chiral symmetry may be restored at high excitation energies. Best agreement is found with a simple mass formula derived within AdS/QCD. Consequences for our understanding of QCD are discussed as well as experiments which may help to decide on the validity of models.

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