强作用与手征规范场

本文引入了e^{ia（x）r_s定域规范变换及相应的规范场.给出了手征规范不变的拉氏函数,并由此出发探讨了手征规范场与强相互作用的联系.在特定条件下可给出唯象的V-A强相互作用形式.}     

从强子动力学模型看高温条件下核物质的新相

从QHD-Ⅱ模型的拉氏量出发,在有限温度场论的框架下,引入核子有效质量和有效化学势,给出了热力学势的平均场结果,分析了状态方程,发现在高温区核物质存在一个新的相变,最后给出了相图.     

QCD手征对称性动力学破缺的有效势研究

本文从无质量夸克的QCD拉氏量出发, 引入双线性外源, 导出了作为复合算子(夸克传播子和胶子传播子)泛函的有效势表示. 从而得出传播子的Dyson-Schwinger方程. 方程具有两组解, 一组解保持手征对称性, 另一组解使手征对称性自发破缺. 通过讨论方程的渐近解, 发现当耦合常数α>1/4时, QCD手征对称性将自发破缺; 当α<1/4时QCD手征对称性仍然保持. 利用求得的夸克自能的渐近行为和f_π介子衰变常数fπ的实验值, 估计了夸克产生的动力学质量和用其它理论方法与实验方法估计得的夸克质量相符, 并对结果进行了讨论.     

Ba2-xLaxTi4O11在静高压下的拉曼振动光谱及软模相变研究

 本文测量了Ba_1.8La_0.2Ti₄O₁₁和Ba_1.6La_0.4Ti₄O₁₁在静高压下的拉曼振动谱，发现了软模的耦合模行为。通过比较Ba₂Ti₄O₁₁的热力学理论计算值和实验数据，确认这种耦合是软模和一个声学模间的耦合，发生的相变是一个由具有B_g对称性的带中心软光学声子驱动的二级铁弹相变。     

多形性相变的分子动力学模拟

 本文利用分子动力学方法研究了KCl晶体在ρ＝ρ₀时的温度相变。面心立方（fcc）和体心立方（bcc）两种结构的径向分布函数随温度的变化的情况说明，在高压下，发生着bcc结构相fcc结构的转变，bcc结构是不稳定的。为了选取合理的势参数，利用了分子动力学程序在T＝0时的性质，计算了NaCl和KCl晶体的零温状态方程，研究了它们在压力作用下发生的多形性相变。计算表明，NaCl和KCl晶体将分别于18.8 GPa和5.9 GPa发生从fcc到bcc的多形性相变，这些值相当接近实验结果。着说明本文选用的势参数势有一定精度的。     

固体C60取向相变的理论研究

本文提出固体Ｃ６０分子间合理的相互作用势模型，利用对称性适函数描述了晶体场及取向模间耦合，并通过自由能的计算得出相变模及与实验相符的取向相变温度。     

FeSiF66H2O晶体的基态能级和零场分裂参量

由单晶的中子衍射方法得到FeS_iF₆6H₂O的晶体结构,这种晶体结构可以用S_iF^6-和Fe(H₂O)⁺⁺两个离子来描述,而局域三角对称的Fe(H₂O)⁺⁺离子反映了这种晶体的主要光谱性质利用不可约张量的理论,构成了晶体场和自旋轨道相互作用哈密顿完全对角化矩阵因此,由完全对角化的晶体场和自旋轨道相互作用哈密顿矩阵和电子顺磁共振的理论公式来求出晶体FeS_iF₆6H₂O中Fe²⁺离子的电子顺磁共振零场分裂参量D和Fa并研究了低自旋³L态对电子顺磁共振(EPR)零场分裂参量的贡献结果显示低自旋³L态对电子顺磁共振的零场分裂参量的贡献是较强的理论计算的结果与实验值是相符的.     

层子质量和Cabibbo角

在SU_L（2）（?）SU_R（2）（?）U（1）理论中,我们讨论了可以在形为e^iα的分立变换下不变的、一般的层子和Higgs粒子相互作用的拉氏量形式。由这些拉氏量我们得到了层子质量间的关系以及层子质量和Cabibbo角之间的关系。     

热标量场等离子体激元阻尼率的临界行为

在闭合时间路径的实时温度场论的框架下,导出了热重整化群方程.热重整化群方程的数值解表明热标量场的耦合常数随温度跑动.将热重整化群方程应用到对称性自发破缺的φ4理论,我们考察了具有有限动量的等离子体激元阻尼率在自发破缺对称性恢复的相变温度下的临界行为.当温度趋于临界温度时,结果表明耦合常数随温度的跑动导致有限动量的等离子体激元阻尼率逐渐减小到零,与不考虑耦合常数随温度的跑动得到的趋势相反.解决了把耦合常数看成常量导致的与临界趋缓规律的矛盾.     

硬脂酸晶体压力效应的FT-IR光谱研究

 本文在0~4 GPa范围内研究了预压力对硬脂酸晶体的相关场劈裂和固态-熔融态相变过程的影响。通过γCH₂面内摇摆振动模和γ'CH₂相关场模的强度和频率变化,发现预压力对晶体内的相关场合分子链取向有明显的影响。预压力对硬脂酸的熔点虽然没有影响,但对γ'CH₂模有“硬化”作用。并且由此出发,对硬脂酸的预熔过程作了讨论。     

Linear bosonic quantum field theories arising from causal variational principles

We describe discrete symmetries of two-dimensional Yang–Mills theory with gauge group G associated with outer automorphisms of G, and their corresponding defects. We show that the gauge theory partition function with defects can be computed as a path integral over the space of twisted G-bundles and calculate it exactly. We argue that its weak-coupling limit computes the symplectic volume of the moduli space of flat twisted G-bundles on a surface. Using the defect network approach to generalised orbifolds, we gauge the discrete symmetry and construct the corresponding orbifold theory, which is again two-dimensional Yang–Mills theory but with gauge group given by an extension of G by outer automorphisms. With the help of the orbifold completion of the topological defect bicategory of two-dimensional Yang–Mills theory, we describe the reverse orbifold using a Wilson line defect for the discrete gauge symmetry. We present our results using two complementary approaches: in the lattice regularisation of the path integral, and in the functorial approach to area-dependent quantum field theories with defects via regularised Frobenius algebras.

     

Breaking of Global Gauge Symmetries on a Spatial-temporal Subdomain

It is generally considered that global gauge symmetry of an action integral over a finite spatial-temporal domain as a whole holds in any subdomain of this domain. However, in this paper we demonstrate that when the so-called localized assumption is no longer valid, the global gauge symmetry will break in the subdomain of this spatial-temporal domain, due to occurrence of a new source called the nonlocal residual. The nonlocal residual is correlated with a gauge field and satisfies the zero mean condition with respect to whole spatial-temporal domain. An example is given to support this conclusion.     

Density wave theory of freezing and the solid

The theory of the liquid to solid transition, in three as well as in two dimensions, is reviewed. The transition can be viewed either as the melting of the solid due to phonon or defect proliferation instabilities or alternatively as freezing of the liquid into a density wave state with crystalline symmetry. A theory due to Yussouff and the author, based on the latter idea, is discussed and its predictions are compared with experiment. It is shown that the theory leads to a new approach to the properties of a deformed (e.g., sheared) solid and of defects such as grain boundaries and dislocations in a solid. The approach brings out explicitly the structural nature of these properties, and is not restricted to small deviations from perfect periodicity (harmonic approximation) since the solid, the liquid and anything in between can be handled theoretically.     

Renormalizable Quantum Gauge Theory of Gravity

The quantum gravity is formulated based on the principle of local gauge invariance. The model discussed in this paper has local gravitational gauge symmetry, and gravitational field is represented by gauge field. In the leading-order approximation, it gives out classical Newton's theory of gravity. In the first-order approximation and for vacuum, it gives out Einstein's general theory of relativity. This quantum gauge theory of gravity is a renormalizable quantum theory.     

Renormalizable Quantum Gauge Theory of Gravity

The quantum gravity is formulated based on the principle of local gauge invariance. The model discussedin this paper has local gravitational gauge symmetry, and gravitational field is represented by gauge field. In the leading-order approximation, it gives out classical Newton‘s theory of gravity. In the first-order approximation and for vacuum,it gives out Einstein‘s general theory of relativity. This quantum gauge theory of gravity is a renormalizable quantumtheory.     

Gravitational Gauge Interactions of Scalar Field

Quantum gauge theory of gravity is formulated based on gauge principle. Because the Lagrangian has strict local gravitational gauge symmetry, gravitational gauge theory is a perturbatively renormalizable quantum theory. Gravitational gauge interactions of scalar field are studied in this paper. In quantum gauge theory of gravity, scalar field minimal couples to gravitational field through gravitational gauge covariant derivative. Comparing the Lagrangian for scalar field in quantum gauge theory of gravity with the corresponding Lagrangian in quantum fields in curved space-time, the definition for metric in curved space-time in geometry picture of gravity can be obtained, which is expressed by gravitational gauge field. In classical level, the Lagrangian and Hamiltonian approaches are also discussed.     

Supersymmetric U(1) Gauge Field Theory with Massive Gauge Field

A new mechanism to introduce the mass of U(1) gauge field in supcrsymmctric U(1) gauge theory is discussed.The modelhas the strict local U(1) gauge symmetry and supersymmetry.Because we introduce two vector superfields simultaneously,the model contains a massive U(1) gauge field as well as a massless U(1) gauge field.     

Liquid-crystal defects and confinement in Yang-Mills theory

It has been shown that, in the Landau gauge of the SU(2) Yang-Mills theory, the residual global symmetry supports the existence of topological vortices which resemble disclination defects in nematic liquid crystals and Alice (half-quantum) vortices in superfluid ³He in the A-phase. The theory also possesses half-integer and integer-charged monopoles, which are analogous to the point-like defects in nematic crystal and in liquid helium. We argue that the deconfinement phase transition in the Yang-Mills theory in the Landau gauge is associated with the proliferation of these vortices and/or monopoles. The text was submitted by the author in English.     

Gravitational Gauge Interactions of Dirac Field

Gravitational interactions of Dirac field are studied in this paper. Based on gauge principle, quantum gauge theory of gravity, which is perturbatively renormalizable, is formulated in the Minkowski space-time. In quantum gauge theory of gravity, gravity is treated as a kind of fundamental interactions, which is transmitted by gravitational gauge field, and Dirac field couples to gravitational field through gravitational gauge covariant derivative. Based on this theory, we can easily explain gravitational phase effect, which has already been detected by COW experiment.