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1.
U. Kasper 《Annalen der Physik》1978,490(3):233-240
We point out that the gravitational field taken by itself cannot be considered as a gauge field. Only an affinity and not a metric can serve as a gauge field. Originally, metric and affinity are completely independent of each other. This fact allows in a natural way to formulate a restricted principle of relativity, according to which only fermion fields may show that there exist a priori distinguished frames of reference. Furthermore, we can couple the gravitational field to boson and fermion fields such that the flat metric or tetrads orthonormalized with respect to this flat metric appearing in the special relativistic matter Lagrangian, are replaced by a Riemannian metric and tetrads orthonormalized with respect to this metric (principle of most minimal gravitational coupling). This coupling principle is a strong restriction on the existence of independent boson fields. Only scalar and vector fields and their different pseudoquantities are possible as independent fields. Boson fields of higher rank are to be considered as fusions of these (pseudo)scalar and (pseudo)vector fields. Theire field equations follow from those of the (pseudo)scalar and (pseudo)vector fields.  相似文献   

2.
The gauge compensation fields induced by the differential operators of the Stueckelberg-Schrödinger equation are discussed, as well as the relation between these fields and the standard Maxwell fields; An action is constructed and the second quantization of the fields carried out using a constraint procedure. The properties of the second quantized matter fields are discussed.  相似文献   

3.
The concept of perturbative gauge invariance formulated exclusively by means of asymptotic fields is generalized to massive gauge fields. Applying it to the electroweak theory leads to a complete fixing of couplings of scalar and ghost fields and of the coupling to leptons, in agreement with the standard theory. The W/Z mass ratio is also determined, as well as the chiral character of the fermions. We start directly with massive gauge fields and leptons and, nevertheless, obtain a theory which satisfies perturbative gauge invariance.  相似文献   

4.
综述了兰州冷却储存环CSRe上转变能洛伦兹因子的测量与校正的最新进展,详细阐述了基于等时性质谱仪实验数据测量储存环的转变能洛伦兹因子的方法,以及利用CSRe二极、四极、六极磁铁校正转变能洛伦兹因子曲线的结果。实验结果表明,二极磁铁和四极磁铁可以平移转变能洛伦兹因子曲线,六极磁铁可以旋转转变能洛伦兹因子曲线。通过校正CSRe的转变能洛伦兹因子曲线,将CSRe对目标离子的质量分辨能力R=m/△m=3.15(9)×104(FWHM)(回旋周期相对误差σT/T=7.3(2)×10-6)提高到1.72(4)×105(FWHM)(σT/T=1.34(3)×10-6)。  相似文献   

5.
The problem of extending fields that are defined on lattices to fields defined on the continua that they become in the continuum limit is basically one of continuous extension from the 0‐skeleton of a simplicial complex to its higher‐dimensional skeletons. If the lattice in question has defects, as well as the order parameter space of the field, then this process might be obstructed by characteristic cohomology classes on the lattice with values in the homotopy groups of the order parameter space. The examples from solid‐state physics that are discussed are quantum spin fields on planar lattices with point defects or orientable space lattices, vorticial flows or director fields on lattices with dislocations or disclinations, and monopole fields on lattices with point defects.  相似文献   

6.
A new variational principle based on the affine connection in space-time is proposed. This leads to a new formulation of general relativity. The gravitational field is a field of inertial frames in space-time. The metricg appears as a momentum canonically conjugate to the gravitational field. In the case of simple matter fields, e.g., scalar fields, electromagnetic fields, Proca fields, or hydrodynamical matter, the new formulation is equivalent to the traditional one. A new formulation of conservation laws is proposed.  相似文献   

7.
《Nuclear Physics B》1995,447(1):183-191
We convert the self-dual model of Townsend, Pilch, and Nieuwenhuizen to a first-class system using the generalized canonical formalism of Batalin, Fradkin, and Tyutin and show that gauge-invariant fields in the embedded model can be identified with observables in the Maxwell-Chem-Simons theory as well as with the fundamental fields of the self-dual model. We construct the phase-space partition function of the embedded model and demonstrate how a basic set of gauge-variant fields can play the role of either the vector potentials in the Maxwell-Chern-Simons theory or the fundamental fields of the self-dual model by appropriate choices of gauge.  相似文献   

8.
Relativistic zero-mass fields are described as manifestly covariant unitary irreducible representations of the Poincaré group. The wave-equations, which are a necessary condition for unitarity, are constructed for spinor fields of arbitrary spin and for tensor fields of integer spin. Poincaré covariance together with causality and positive energy are used to determine the commutators of quantized fields up to a positive multiple and to prove the spin-statistics theorem. The use of potentials for boson fields is discussed and it is shown that, at the expense of manifest covariance, potentials may be introduced as zero-mass limits of the massive Wigner representations.  相似文献   

9.
Vectorial fields with position-independent stochastic behavior within a certain region are analyzed. More specifically, we deal with the transverse components of this class of beamlike fields (the longitudinal component assumed to be negligible). The general form of the cross-spectral density tensor (CDT) of these fields is shown. Attention is also focused on the properties of these kinds of fields. Thus, among other characteristics, it is seen that the CDT of these fields can be written as the sum of two CDTs associated, respectively, to a totally polarized field and to an unpolarized field. It is also shown that, for such fields, a Young's interference experiment can always be performed whose fringe visibility is optimized. This behavior has analytically been characterized by means of a certain parameter, valid for general beamlike fields. It is shown that, for the fields studied, this parameter reaches its maximum value.  相似文献   

10.
李晓杰  刘中强  王春阳  徐玉良  孔祥木 《物理学报》2015,64(24):247501-247501
近年来, 磁性纳米管的物理性质和相关应用得到了人们的广泛关注. 利用有效场理论研究了纳米管上双模随机晶场中Blume-Capel模型的磁化强度和相变性质, 得到了系统的磁化强度与温度和随机晶场的关系及其相图. 结果表明: 系统在稀释晶场、交错晶场和同向晶场中会表现出不同的磁学性质和相变行为; 稀释晶场和交错晶场会抑制系统的磁化强度, 导致其基态饱和值小于1, 而同向晶场则不会; 随着随机晶场参量的变化, 系统存在多个相变温度, 并呈现出三临界现象和重入现象.  相似文献   

11.
We consider polygonal Markov fields originally introduced by Arak and Surgailis (Probab. Theory Relat. Fields 80:543–579, 1989). Our attention is focused on fields with nodes of order two, which can be regarded as continuum ensembles of non-intersecting contours in the plane, sharing a number of features with the two-dimensional Ising model. We introduce non-homogeneous version of polygonal fields in anisotropic environment. For these fields we provide a class of new graphical constructions and random dynamics. These include a generalized dynamic representation, generalized and defective disagreement loop dynamics as well as a generalized contour birth and death dynamics. Next, we use these constructions as tools to obtain new exact results on the geometry of higher order correlations of polygonal Markov fields in their consistent regime. Research supported by the Polish Minister of Science and Higher Education grant N N201 385234 (2008-2010).  相似文献   

12.
In this paper, we study the influences of magnetic fields on the coexistence of diquark and chiral condensates in an extended Nambu–Jona–Lasinio model with QCD axial anomaly, as it relates to color-flavor-locked quark matter. Due to the coupling of rotated-charged quarks to magnetic fields, diquark condensates become split, and the coexistence region is thus superseded in favor of a specific diquark Bose–Einstein condensation (BEC), denoted as the BECI phase. For strong magnetic fields, we find that the BECI transition is pushed to larger quark chemical potentials. The effect of magnetic catalysis tends to disrupt the BEC–BCS (Bardeen–Cooper–Schrieffer) crossover predicted in previous works. For intermediate fields, the effect of inverse magnetic catalysis is observed, and the axial-anomaly-induced phase structure is essentially unchanged.  相似文献   

13.
由散斑场和参考光的干涉图样提取散斑场复振幅、相位和强度的数值分布,并对其统计特性进行实验研究,消除了散斑场强度统计函数特别是概率密度函数的传统测量方法中噪声引起的偏差,并实现了散斑场复振幅和相位统计特性的实验研究.通过对不同散射角处散斑场的研究发现随着散射角度的增大散斑颗粒逐渐呈现出横向展宽的现象,且其平均宽度表现为各向异性,但是其概率密度函数并没有发生变化,与小角度情况一样属于圆形高斯散斑场. 关键词: 散斑 概率密度 干涉  相似文献   

14.
采用密度泛函理论,在B3LYP/6-311++G(d,p)基组水平上对分子进行优化,研究了在不同外电场下,哈龙1211分子的键长、体系总能量、偶极矩、能级、能隙、电荷分布和红外光谱的变化规律.计算结果表明,电场方向不同,键长的变化趋势也不同.随着外电场(-0.02 a.u.-0.03 a.u.)的增加,C-Br间的键长随x轴方向电场的增加可能先趋于断裂,而C-Cl间的键长随y轴方向电场的增加可能最先趋于断裂,这对利用外电场解离哈龙1211分子有着重要意义.体系总能量和能隙随着外电场的增加先增大后减小,而偶极矩的变化趋势相反.另外,随着电场的增加,红外光谱的最强峰先发生蓝移再发生红移.  相似文献   

15.
For free nonradiation zero rest-mass fields, as for example the nonnull Maxwell and the Weyl tensor fields in vacuum, a uniform treatment of the behavior of the principal null vectors in the vicinity of boundary zeros is given. It is shown that a boundary zero of a field is a singular point of at least one of its principal null vectors. In the special case of a Maxwell field for which the Poynting three-vector vanishes for a certain observer-field, a boundary zero of the Maxwell field is a singular point of the corresponding electric and magnetic fields. The results are valid in flat and curved spacetimes independently of whether the zero rest-mass fields act as source of the spacetime curvature or not.  相似文献   

16.
The effect of particle creation by nonstationary external fields is considered as a radiation effect in the expectation-value spacetime. The energy of created massless particles is calculated as the vacuum contribution in the energy-momentum tensor of the expectation value of the metric. The calculation is carried out for an arbitrary quantum field coupled to all external fields entering the general second-order equation. The result is obtained as a functional of the external fields. The paper gives a systematic derivation of this result on the basis of the nonlocal effective action. Although the derivation is quite involved and touches on many aspects of the theory, the result itself is remarkably simple. It brings the quantum problem of particle creation to the level of complexity of the classical radiation problem. For external fields like the electromagnetic or gravitational field there appears a quantity, the radiation moment, that governs both the classical radiation of waves and the quantum particle production. The vacuum radiation of an electrically charged source is considered as an example. The research is aimed at the problem of backreaction of the vacuum radiation.  相似文献   

17.
The formation of the functional operator procedure for solving the problem of the propagation of random fields generated by extraneous sources in a statistically inhomogeneous continuous medium is considered. The solution is represented in the form of a probability density functional or a characteristic functional as the basis for analyzing the likelihood ratio. The structure of operators introduced in the calculations correlates with the statistical properties of both the fields of random sources and the parameters of the propagation medium. In the framework of Gaussian models of sources and propagation parameters, the solution is constructed in a closed form. Representations for the mean fields and their correlation functions are derived.  相似文献   

18.
Ultrasound has the potential to be broadly applied in the field of agricultural food processing due to advantages such as environmental friendliness, low energy costs, no need for exogenous additives and ease of operation. High-frequency ultrasound is mainly used in medical diagnosis and in the food industry for the identification of ingredients and production line quality testing, while low-frequency ultrasounds is mainly used for extraction and separation, accelerating chemical reactions, auxiliary microbial fermentation and quality enhancement in food industry. Magnetic fields have many advantages of convenient use, such as non-toxic, nonpolluting and safe. High-intensity pulsed magnetic fields are widely used as a physical non-thermal sterilization technology in food processing, while weak magnetic fields are better at activating microorganisms and promoting their growth. Ultrasound and magnetic fields, due to their positive biological effects, have a wide range of applications in the food processing industry. This paper provides an overview of the research progress and applications of ultrasound and magnetic fields in food processing from the perspectives of their biological effects and mechanisms of action. Additionally, with the development and application of physical field technology, physical fields can now be used to provide significant technical advantages for assisting fermentation. Suitable physical fields can promote the growth of microbial cells, improve mycelial production and increase metabolic activity. Furthermore, the current status of research into the use of ultrasound and magnetic field technologies for assisting the fermentation of rare edible fungi, is discussed.  相似文献   

19.
All possible iron environments with respect to nearest neighbour vacancies in vacancy-ordered and vacancy-disordered maghemite have been evaluated and used as the foundation for a crystallographically-based analysis of the published NMR spectra of maghemite. The spectral components have been assigned to particular configurations and excellent agreement obtained in comparing predicted spectra with published spectra taken in applied magnetic fields. The broadness of the published NMR lines has been explained by calculations of the magnetic dipole fields at the various iron sites and consideration of the supertransferred hyperfine fields.  相似文献   

20.
采用密度泛函理论,在B3LYP/6-311++G(d,p)基组水平上对分子进行优化,研究了在不同外电场下,哈龙1211分子的键长、体系总能量、偶极矩、能级、能隙、电荷分布和红外光谱的变化规律。计算结果表明,电场方向不同,键长的变化趋势也不同。随着外电场(-0.02a.u.—0.03a.u.)的增加,C-Br间的键长随x轴方向电场的增加可能先趋于断裂,而C-Cl间的键长随y轴方向的增加可能最先趋于断裂,这对利用外电场解离哈龙1211分子有着重要意义。体系总能量和能隙随着外电场的增加先增大后减小,而偶极矩的变化趋势相反。另外,随着电场的增加,红外光谱的最强峰先发生蓝移再发生红移。  相似文献   

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