Ionization Problem for Hydrogen Atom in Intense Circularly Polarized Laser Field Revisited

Ionization rate for circular polarization laser field is reformulated in length gauge. The Volkov state or the Coulomb-correctsd Volkov one is served at the final wavefunction and would lead to that the ionization rate in length gauge is closer to the experimental data than the corresponding result in velocity gauge. It is also found that the ionization rate as a function of laser intensity has nevertheless the stabilization effect, although in the sense more weakly in length gauge than in velocity gauge, when the field is to be comparable or exceeds to the atomic binding field.     

New Mechanism for Mass Generation of Gauge Field

A new mechanism for mass generation of gauge field is discussed in this paper.By introducing two sets of gauge fields and making the variations of these two sets of gauge fields compensated each other under local gauge transformations,the mass term of gauge fields is introduced into the Lagrangian without violating the local gauge symmetry of the Lagrangian.This model is a renormalizable quantum model.     

多壁碳纳米管薄膜的压阻效应研究

对多壁碳纳米管薄膜的压阻效应进行了研究. 实验所用的多壁碳纳米管用热灯丝化学气相沉积法合成, 压阻效应用三点弯曲法测量. 研究发现: 在室温下与500微应变内, 原始的多壁碳纳米管薄膜无明显压阻效应, 而经化学修饰处理的碳纳米管膜的压阻因子最高可达120左右, 大大超过多晶硅(Si)在35°C时的压阻因子30, 并且压阻因子与制备方法密切相关. 重点讨论了多壁碳纳米管薄膜产生压阻效应的机制.     

Pair Production in Chromoelectric Field with Back Reaction

Massless quark pair production in SU(2) gauge chromoelectric field is investigated by solving the Wigner function with back reaction. The temporal evolution of specific field and its current are obtained self consistently. For the quark distribution function, both its time and momentum dependence are studied. In particular, some interesting phenomena are found, for example, the more abundant symmetry or/and antisymmetry characteristics, the existence of the attractive basin structure and the existence of the momentum "gap" in the quark distribution and so on. All the phenomena are associated with the quark-gluon plasma oscillation, which due to the back reaction effect. The study and analysis qualitatively about the components of the Wigner function are expected to be helpful to deepen the understanding of the QCD vacuum.     

Renormalization of a gauge theory in a nonlinear gauge

We discuss renormalization of an O(3) gauge model with the gauge fixing term given by ℒ_g.f.=-1/ζ|(∂_μ-igA ₃ ^μ )W ^+μ|²-(1/2α)(∂A ³)². We utilize earlier results on the general theory of renormalization of gauge theories in quadratic gauges to prove multiplicative renormalizability of the theory together with a subtractive renormalization of gauge fixing and ghost terms. We show that this model has a double BRS invariance and that it is preserved under renormalization.     

悬臂梁微小形变电测法实验中的力学结构优化设计

悬臂梁微小形变的电测法是大学物理实验课程中重要的综合应用型实验之一.由于课程内容的需要,一般忽略砝码加载后的悬臂梁变形,因此必须在应变可测的前提下,悬臂梁的变形角足够小.文章通过对悬臂梁设计厚度和长度的优化计算,使得在较小的悬臂梁变形角和较小的砝码重量条件下,应变可以被常用单臂电桥较为精确的测量,实现了该实验的测量准确度和仪器装置可操作性的最佳平衡.     

材料力学基本实验中应变片粘贴误差分析

根据任意方向的应变公式,分析了材料力学基本实验中应变片粘贴方向、位置误差对测量结果的影响。     

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.     

Action Principle and Algebraic Approach to Gauge Transformations in Gauge Theories

The action principle is used to derive, by an entirely algebraic approach, gauge transformations of the full vacuum-to-vacuum transition amplitude (generating functional) from the Coulomb gauge to arbitrary covariant gauges and in turn to the celebrated Fock–Schwinger (FS) gauge for the Abelian (QED) gauge theory without recourse to path integrals or to commutation rules and without making use of delta functionals. The interest in the FS gauge, in particular, is that it leads to Faddeev–Popov ghosts-free non-Abelian gauge theories. This method is expected to be applicable to non-Abelian gauge theories including supersymmetric ones.     

Expansion of EYM amplitudes in gauge invariant vector space

Motivated by the problem of expanding the single-trace tree-level amplitude of Einstein-Yang-Mills theory to the BCJ basis of Yang-Mills amplitudes, we present an alternative expansion formula in gauge invariant vector space. Starting from a generic vector space consisting of polynomials of momenta and polarization vectors, we define a new sub-space as a gauge invariant vector space by imposing constraints on the gauge invariant conditions. To characterize this sub-space, we compute its dimension and construct an explicit gauge invariant basis from it. We propose an expansion formula in this gauge invariant basis with expansion coefficients being linear combinations of the Yang-Mills amplitude, manifesting the gauge invariance of both the expansion basis and coefficients. With the help of quivers, we compute the expansion coefficients via differential operators and demonstrate the general expansion algorithm using several examples.     

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.     

冲击加载下材料破坏准则的规范场理论

 本文给出了规范场理论中的Bessel-Hagen散度不变性的广义E. Noether对称定理。应用此定理及缺陷的规范场理论，研究了材料在强动外载作用下的动力学性质，给出了破坏准则的一般公式，此公式定量地反映了缺陷和外载对材料破坏的影响。作为一个例子，研究了强冲击波作用下材料的破坏情况，使一般公式具体化了，而且定量地反映了冲击波的速度、压力和缺陷对材料破坏的影响。     

Twisted Gauge Theories

Gauge theories on a space-time that is deformed by the Moyal–Weyl product are constructed by twisting the coproduct for gauge transformations. This way a deformed Leibniz rule is obtained, which is used to construct gauge invariant quantities. The connection will be enveloping algebra valued in a particular representation of the Lie algebra. This gives rise to additional fields, which couple only weakly via the deformation parameter θ and reduce in the commutative limit to free fields. Consistent field equations that lead to conservation laws are derived and some properties of such theories are discussed.     

Gauge Transformation and Constraint Induced Operator Ordering for Charged Rigid Planar Rotator in Uniform Magnetic Field

When the motion of a particle is constrained, excess terms exist using hermitian form of Cartesian momentum pi （i=1, 2,3） in usual kinetic energy （1/2/μ）∑ pi^2 , and the correct kinetic energy turns out to be （1/2μ） ∑1/ fipi f ipi, where fi are dummy factors in classical mechanics and nontrivial in quantum mechanics. In this paper the explicit form of the dummy functions fi is given for a charged rigid planar rotator in the uniform magnetic field with different gauge chosen. Under different gauges, we have different sets of dummy factors. It means that these factors do not have direct observable effect.     

Entanglement dynamics in two-component Bose--Einstein condensates

Based on the exact solution of the time-dependent Schr\"{o}dinger equation for two-species Bose--Einstein condensates (BECs) consisting of two hyperfine states of the atoms coupled by a tuned adiabatic and time-varying Raman coupling, we obtain analytically the entanglement dynamics of the system with various initial states, particularly the SU(2) coherent state, for both of cases with and without the nonlinear interactions. It is shown that the effect of nonlinear interaction on the entanglement appears only in a longer time period depending on the BEC parameters.     

Synchronization Gauges and the Principles of Special Relativity

The axiomatic bases of Special Relativity Theory (SRT) are thoroughly re-examined from an operational point of view, with particular emphasis on the status of Einstein synchronization in the light of the possibility of arbitrary synchronization procedures in inertial reference frames. Once correctly and explicitly phrased, the principles of SRT allow for a wide range of theories that differ from the standard SRT only for the difference in the chosen synchronization procedures, but are wholly equivalent to SRT in predicting empirical facts. This results in the introduction, in the full background of SRT, of a suitable synchronization gauge. A complete hierarchy of synchronization gauges is introduced and elucidated, ranging from the useful Selleri synchronization gauge (which should lead, according to Selleri, to a multiplicity of theories alternative to SRT) to the more general Mansouri–Sexl synchronization gauge and, finally, to the even more general Anderson–Vetharaniam–Stedmans synchronization gauge. It is showed that all these gauges do not challenge the SRT, as claimed by Selleri, but simply lead to a number of formalisms which leave the geometrical structure of Minkowski spacetime unchanged. Several aspects of fundamental and applied interest related to the conventional aspect of the synchronization choice are discussed, encompassing the issue of the one-way velocity of light in inertial and rotating reference frames, the global positioning system (GPS)s working, and the recasting of Maxwell equations in generic synchronizations. Finally, it is showed how the gauge freedom introduced in SRT can be exploited in order to give a clear explanation of the Sagnac effect for counter-propagating matter beams.     

Collective Diffusion and Strange-Metal Transport

We study a particular combination of charge and heat currents, which is decoupled with the heat current. The "heat-decoupled" (HD) current can be transported by diffusion at long distances, when the thermoelectric effect is small, large, or balanced. Using holographic models with momentum relaxation, we illustrate that the different thermoelectric effects correspond to the high temperatures and strong disorder, low temperatures, or special critical index. Meanwhile, the Einstein-like relation and the diffusion/chaos relation may be emergent. Assuming that the existence and features of HD modes appear in strange metals, we can predict that when the thermoelectric effect is not very large, the scaling of resistivity is predominantly controlled by the HD susceptibility and chaos; otherwise more physics is required.     

电磁量计随爆轰波运动惯性性质的二维数值模拟

 利用二维非线性有限元动力分析程序,对金属电磁测速量计在爆轰波质速测量中随爆轰波运动的惯性性质进行了二维数值模拟。     

The linear system for self-dual gauge fields in a spacetime of signature 0

The overdetermined linear system for the self-dual Yang—Mills (SDYM) equations is examined in a flat four-dimensional space whose metric has signature 0. There are three different domains for the system, and correspondingly three (essentially) different solutions to the linear system for a given gauge field. If the gauge potential is real analytic, two of the solutions patch together to give a holomorphic function in an annular region of projective twistor space. Conversely, an arbitrary holomorphic GL(n, )-valued function in such a domain can be uniquely factored (on the real lines) to give a solution to SDYM with gauge group U(n). The set of all real analytic u(n)-valued gauge fields can thus be parametrized by the points of a certain double coset space.