arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 0706.3288hep-phhep-exnucl-exnucl-th
收藏

激发态重子手征恢复的另一实验证据

Alternative experimental evidence for chiral restoration in excited baryons

L. Ya. Glozman

备注：
4 pp. A new footnote with an alternative proof of impossibility of parity doublet decay into pi + N is added. To appear in Phys. Rev. Lett
发表信息：
Phys.Rev.Lett.99:191602,2007
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

根据现有的激发态强子的经验谱型，有人提出在零温度/密度下，激发态强子的手征对称性近似恢复（有效对称性恢复）。如果正确的话，这意味着激发态强子的质量产生机制和物理与最低态相比是非常不同的。人们需要另一种独立的实验信息来证实这一猜想。利用非常一般的手征对称性论证，证明了在给定的激发核子中严格的手征恢复禁止它衰变到N π通道中。因此，那些从光谱图中被假定为近似手征多重态的激发态核子，必定只“微弱地”衰变到N π通道中，（f_{N^*Nπ} / f_{NNπ}）^2 << 1。然而，那些没有手征伙伴的重子必须以与f_{NNπ}相当的衰变常数强烈衰变。衰减常数可以从现有的衰减宽度和分支比中提取。结果表明，对于所有已建立的手征二重态N_+（1440）- N_-（1535），N_+（1710）- N_-（1650），N_+（1720）- N_-（1700），N_+（1680）- N_-（1675），N_+（2220）- N_-（2250），N_+（？）- N_-（2190），N_+（？）- N_-（2600），高自旋态的比值为（f_{N^*Nπ} / f_{NNπ}）^2 ~ 0.1或更小。与此相反，唯一一个已被证实的激发态核子N（1520），它的手征伙伴不能从光谱数据中识别出来，它在Nπ通道中的衰减常数与f_{NNπ}相当。这给出了一个独立的实验验证的手征对称性恢复方案。

英文摘要：

Given existing empirical spectral patterns of excited hadrons it has been suggested that chiral symmetry is approximately restored in excited hadrons at zero temperature/density (effective symmetry restoration). If correct, this implies that mass generation mechanisms and physics in excited hadrons is very different as compared to the lowest states. One needs an alternative and independent experimental information to confirm this conjecture. Using very general chiral symmetry arguments it is shown that strict chiral restoration in a given excited nucleon forbids its decay into the N πchannel. Hence those excited nucleons which are assumed from the spectroscopic patterns to be in approximate chiral multiplets must only "weakly" decay into the N πchannel, (f_{N^*Nπ}/f_{NNπ})^2 << 1. However, those baryons which have no chiral partner must decay strongly with a decay constant comparable with f_{NNπ}. Decay constants can be extracted from the existing decay widths and branching ratios. It turnes out that for all those well established excited nucleons which can be classified into chiral doublets N_+(1440) - N_-(1535), N_+(1710) - N_-(1650), N_+(1720) - N_-(1700), N_+(1680) - N_-(1675), N_+(2220) - N_-(2250), N_+(?) - N_-(2190), N_+(?) - N_-(2600), the ratio is (f_{N^*Nπ}/f_{NNπ})^2 ~ 0.1 or much smaller for the high-spin states. In contrast, the only well established excited nucleon for which the chiral partner cannot be identified from the spectroscopic data, N(1520), has a decay constant into the Nπchannel that is comparable with f_{NNπ}. This gives an independent experimental verification of the chiral symmetry restoration scenario.

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。

↑