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5月26日,诺贝尔物理奖得主,著名华裔物理学家,美国哥伦比亚大学教授李政道院土,应邀在中国科学院研究生院做了一个题为“真空作为一个物理媒质”的学术报告。精辟地论证了当前物理学面临的两大疑难,并在这世纪之交的激动人心的时刻,提出了发人深思的问题:“我们将给下一世纪的下一代人留下什么?” 报告首先从李政道教授在50年代曾经做出过巨大贡献的,粒子物理学中左和右的不对称性(宇称不守恒)讲起。 相似文献
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1983年标志着粒子物理发展史中特别引人注目的十年的结束.在从1973年开始的这十年中,有三个特别重要的,或许可以说具有历史意义的成就.它们是: 1.理论上与实验上实现了控制所有电磁现象和弱相互作用的力的统一. 2.认识到强相互作用粒子(核子、介子和其他强子)事实上是由称为夸克的更小的组分构成的,并发展了一种关于夸克之间作用力的初步理论. 3.承认存在着除了质量外其它性质几乎完全相同的三代基本粒子族.每一代包括两个夸克,一个带电轻子(电子、μ子和τ子)和一个中微子. 电磁力和弱力的这种统一理论与强相互作用的初步理论一起,称为“标… 相似文献
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The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ→γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G(p) with the form of 285500/(m 2 π + p 2 ) should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ→π 0 pp process is also discussed. 相似文献
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最近应科学出版社之约,我们翻译了2004年诺贝尔奖得主、著名理论物理学家维尔切克(F.Wilczeck)的一部高级科普著作《神奇的现实》(Fantastic Realities)。这本书是作者三十年来认真思考物理世界的产物,以丰富的内容、广博的知识、深邃的见解以及独特的视角向热爱物理的广大读者介绍了现代物理的方方面面。作者希望借此书拓展知识前沿,用美妙的现代物理概念丰富读者的生活,特别是激励更多的年轻人投身于物理学的研究。译书即将出版了,但却留下了一些遗憾之处。这是因为考虑到篇幅和难度,出版社决定舍弃原著中的某些章节,而这几章对于普及和深化理解现代物理却是非常重要的。我们得到了原作者的首肯,从舍弃的章节中挑选了部分章节翻译发表。现在刊登的这一部分,专门讨论了量子场论的发生与发展。按照原书中作者的建议,我们取名为《量子场论通俗入门》。 相似文献
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We indicated in our previous work that for QED the role of the scalar potential which appears at the loop level is much smaller than that of the vector potential and is in fact negligible. But the situation is different for QCD, one reason is that the loop effects are more significant because α s is much larger than α, and second the non-perturbative QCD effects may induce a sizable scalar potential. In this work, we study phenomenologically the contribution of the scalar potential to the spectra of charmonia, bottomonia and b(c) families. Taking into account both vector and scalar potentials, by fitting the well measured charmonia and bottomonia spectra, we re-fix the relevant parameters and test them by calculating other states of not only the charmonia and bottomonia families, but also the b family. We also consider the Lamb shift of the spectra. 相似文献
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