周光召对理论物理和原子能事业的贡献

2019年5月15日,周光召先生迎来90华诞。他是国际知名理论物理学家,在中国核武器理论设计和人才培养方面发挥了重要作用,同时也是中华人民共和国改革开放以后科技事业发展的领导者。本文旨在评述周光召在理论物理方面的贡献,重点介绍其在杜布纳联合原子核研究所工作期间的基本粒子理论研究,及其重返理论物理学界后在凝聚态和统计物理、量子场论和粒子物理等方面的工作。     

所有基本相互作用力统一的一个模型

提出了一个统一强、电磁、弱和引力 4种基本相互作用的模型 .普通 4维时空的切空间是由 4个标架场支撑的 1 4维内部时空的一个子流形 .粒子物理标准模型和引力的统一由内部空间的规范对称性来描述 .     

普遍的Chern-Simons链和它们的应用

本文将Chern形式按它子流形上的外微分形式的阶数展开, 很容易地给出了一些Chern-Simons链. 并讨论了某些约束条件下, 子流形间Chern形式的递推关系和它们的一些应用.     

Note on Higgs Decay into Two Photons H → γγ

The Higgs decay H →γγ due to the virtual W-loop effect is revisited in the unitary gauge by using the symmetry-preserving and divergent-behavior-preserving loop regularization method,which is realized in the fourdimensional space-time without changing original theory.Though the one-loop amplitude of H →γγ is finite as the Higgs boson in the standard model has no direct interaction with the massless photons at tree level,it involves both tensor-type and scalar-type divergent integrals which can in general destroy the gauge invariance without imposing a proper regularization scheme to make them well-defined.As the loop regularization scheme can ensure the consistency conditions between the regularized tensor-type and scalar-type divergent irreducible loop integrals to preserve gauge invariance,we explicitly show the absence of decoupling in the limit M W /M H → 0 and obtain a result agreeing exactly with the earlier one in the literature.We then clarify the discrepancy of the earlier result from the recent one obtained by R.Gastmans,S.L.Wu and T.T.Wu.The advantage of calculation in the unitary gauge becomes manifest in that the non-decoupling arises from the longitudinal contribution of the W gauge boson.     

Pati超弦前子模型的等级结构

本文就Pati的最小前子模型^[1—3]的对称性演变模式进行了系统的讨论. 给出了一个比较优越的方案.     

Flavor non-universal gauge interactions and anomalies in B-meson decays

Motivated by flavor non-universaity and anomalies in semi-leptonic B-meson decays, we present a general and systematic discussion about how to construct anomaly-free U(1)' gauge theories based on an extended standard model with only three right-handed neutrinos. If all standard model fermions are vector-like under this new gauge symmetry, the most general family non-universal charge assignments,(a,b,c) for three-generation quarks and(d,e,f)for leptons, need satisfy just one condition to be anomaly-free, 3(a+b+c) =-(d+e+f). Any assignment can be linear combinations of five independent anomaly-free solutions. We also illustrate how such models can generally lead to flavor-changing interactions and easily resolve the anomalies in B-meson decays. Probes with B_s-B_s mixing, decay into τ~±, dilepton and dijet searches at colliders are also discussed.     

宇称破坏与对称原理

六十五年前李政道和杨振宁提出了具有划时代意义的弱相互作用中宇称不守恒定律,随后得到吴健雄等人实验的验证,彻底打破了人们关于对称原理的认识和理解,对称原理不再仅仅是包含对称性和守恒律.从此,对称破缺与对称性共同构成对称原理,成为自然界遵循的普遍规律.