相对论力学系统的形式不变性与Lie对称性

研究相对论力学系统的形式不变性和Lie对称性.给出相对论力学系统在无限小变换下形式不变性和Lie对称性的定义、判据和守恒量,得到形式不变性和Lie对称性的关系,并举例说明结果的应用. 关键词： 相对论 力学系统 形式不变性 Lie对称性     

相对论力学系统的形式不变性与Noether对称性

研究相对论力学系统的形式不变性与Noether对称性，给出相对论力学系统的Noether定理， 以及形式不变性的定义、判据和守恒量，得到形式不变性和Noether对称性的关系，并举例 说明结果的应用- 关键词： 相对论 力学系统 形式不变性 Noether对称性     

Conformal invariance of quantum fields in two-dimensional space-time

Our investigations of conformal invariance are based on the theory of analytic representations of the conformal group and its universal covering group. With its help the action of the conformal group on free massless fields, Greenberg fields, Wick products of these fields, and the Thirring fields is studied. In this context we find an infinite set of new operator solutions for the Thirring model that are all equivalent to each other. Explicit constructions of the nonlocal special conformal transformations of all these fields are given.     

Spontaneous reduction of noncommutative gauge symmetry and model building

We propose a mechanism for the spontaneous (gauge-invariant) reduction of noncommutative gauge theories down to SU(n). This can be achieved through the condensation of composite gauge invariant fields that involve half-infinite Wilson lines in the trace-U(1) noninvariant and SU(n) preserving direction. Based on this mechanism, we discuss an anomaly-free fully gauge invariant noncommutative standard model based on the minimal gauge group , previously proposed, and show how it can be consistently reduced to the standard model with the usual particle spectrum. Charge quantization for quarks and leptons naturally follows from the model.     

Contractions of space-time groups and relativistic quantum mechanics

The relation of the conformal group to various earlier proposed relativistic quantum mechanical dynamical groups (and other related groups) is studied in the framework of projective geometry, by explicitly constructing the contractions of the six-dimensional coordinate transformations. Five-dimensional realizations are then derived. An attempt is made to improve our physical insight through geometry.     

C, P, and T invariance of noncommutative gauge theories

In this paper we study the invariance of the noncommutative gauge theories under C, P, and T transformations. For the noncommutative space (when only the spatial part of straight theta is nonzero) we show that noncommutative QED (NCQED) is parity invariant. In addition, we show that under charge conjugation the theory on noncommutative R(4)(straight theta) is transformed to the theory on R(4)(-straight theta), so NCQED is a CP violating theory. The theory remains invariant under time reversal if, together with proper changes in fields, we also change straight theta by -straight theta. Hence altogether NCQED is CPT invariant. Moreover, we show that the CPT invariance holds for general noncommutative space-time.     

Non locality and gauge invariance in relativistic wave equations

Linear relativistic wave equations are discussed with consideration of the adjoint wave function and its effect on the equations of motion and charge-current 4-vector.Invited talk presented at the International Symposium Selected Topics in Quantum Field Theory and Mathematical Physics, Bechyn, Czechoslovakia, June 14–19, 1981.     

Existence and invariance of twisted products on a symplectic manifold

It is now well-known [1] that the twisted product on the functions defined on a symplectic manifold, play a fundamental role in an invariant approach of quantum mechanics. We prove here a general existence theorem of such twisted products. If a Lie group G acts by symplectomorphisms on a symplectic manifold and if there is a G-invariant symplectic connection, the manifold admits G-invariant Vey twisted products. In particular, if a homogeneous space G/H admits an invariant linear connection, T ^*(G/H) admits a G-invariant Vey twisted product. For the connected Lie group G, the group T ^*G admits a symplectic structure, a symplectic connection and a Vey twisted product which are bi-invariant under G.     

Gauge invariance and spontaneous symmetry breaking in two-gap superconductors

The gauge symmetry of the Ginzburg–Landau theory for two-gap superconductors is analyzed in this letter. We argue that the existence of two different phases, associated with the two independent scalar Higgs fields, explicitly breaks the gauge symmetry of the Ginzburg–Landau Hamiltonian, unless a new additional vector field is included. Furthermore, the interference term, or Josephson coupling, holding a direct dependence with the phase difference, also explicitly breaks down the gauge symmetry. We show that a solution for the problem is achieved by adding an additional kinetic coupling term between the two vector fields, which generates the desired terms through a spontaneous symmetry breaking mechanism. Finally, the electrodynamics of the system is also presented in terms of the supercurrents inside the superconducting region.     

Interacting twisted and untwisted scalar fields in a nonsimply connected space-time

Interacting twisted and untwisted scalar fields are studied in a non-Minkowskian space-time with the topology S¹ × R³. Renormalization of the theory is discussed, and the oneloop effective potential is calculated and used to discuss symmetry breaking and mass generation as a consequence of the non-trivial topology. It is found that an interaction between the twisted and untwisted fields can lead to symmetry breaking.     

Lie symmetry and Mei symmetry of a rotational relativistic system in phase space

The Lie symmetry and the Mei symmetry of a rotational relativistic system in phase space are studied. The definition, criterion and conserved quantity of the Lie symmetry and the Mei symmetry of a rotational relativistic system in phase space are given. The relation between the Lie symmetry and the Mei symmetry is found. An example is given to illustrate the application of the result.     

Dilatation invariance and spontaneous symmetry breakdown in dimensional renormalization

This paper completes a systematic study of the renormalization of scale invariant models with spontaneous symmetry breakdown discussing an effective scheme for the construction of Feynman amplitudes. From a general point of view the original scale invariance of the models is accounted for by constraining the dilation anomalies with a minimality criterion analyzed in a previous paper. This criterion is basd on a local Ward identity where the anomalies appear oupled to a spurion field. Here the general framework is adapted to a dimensional renormalization scheme and it is shown to be equivalent to a scale invariant choice of all counterterms and as it happens in minimal schemes, to the mass independence of the renormalization constants, thereby allowing a derivation of a renormalization group equation with standard (mass independent) coefficients. The whole analysis refers as an example to the simplest bosonic model containing all the features common to scale invariant theories with spontaneous symmetry breakdown.     

转动相对论系统的Appell方程及其形式不变性

给出转动相对论系统的Appell方程,讨论相对论力学的四个新型基本动力学函数 在无限小群变换下研究转动相对论系统Appell方程的形式不变性,给出定义和判据 研究形式不变性与Noether对称性与Lie对称性的关系,寻求转动相对论系统的守恒量 关键词： 转动相对论 Appell方程 形式不变性 对称性与守恒量     

Reparametrization invariance: a gauge-like symmetry of ultrametrically organised states

The reparametrization transformation between ultrametrically organised states of replicated disordered systems is explicitly defined. The invariance of the longitudinal free energy under this transformation, i.e. reparametrization invariance, is shown to be a direct consequence of the higher level symmetry of replica equivalence. The double limit of infinite step replica symmetry breaking and is needed to derive this continuous gauge-like symmetry from the discrete permutation invariance of the n replicas. Goldstone's theorem and Ward identities can be deduced from the disappearance of the second (and higher order) variation of the longitudinal free energy. We recall also how these and other exact statements follow from permutation symmetry after introducing the concept of “infinitesimal" permutations. Received 21 July 2000     

非对易时空下Gibbons-Maeda dilaton黑洞和Garfinkle-Horowitz-Strominger dilaton黑洞的热力学性质

以Gibbons-Maeda dilaton黑洞和Garfinkle-Horowitz-Strominger dilaton黑洞为例，研究空间的非对易性对黑洞热力学性质的影响.通过对比对易时空中Gibbons-Maeda dilaton黑洞和非对易时空中Garfinkle-Horowitz-Strominger dilaton黑洞的温度，得出如下结论：从对黑洞热力学性质产生影响这一角度来说，时空的非对易性和黑洞的荷(电荷或磁荷)有相似的作用.     

Conformal invariance and Noether symmetry, Lie symmetry of holonomic mechanical systems in event space

This paper is devoted to studying the conformal invariance and Noether symmetry and Lie symmetry of a holonomic mechanical system in event space. The definition of the conformal invariance and the corresponding conformal factors of the holonomic system in event space are given. By investigating the relation between the conformal invariance and the Noether symmetry and the Lie symmetry, expressions of conformal factors of the system under these circumstances are obtained, and the Noether conserved quantity and the Hojman conserved quantity directly derived from the conformal invariance are given. Two examples are given to illustrate the application of the results.     

Chaplygin系统的Noether对称性与形式不变性

利用d’AlembertLagrange原理的Chaplygin形式在无限小变换下的变形形式得到Chaplygin系统的广义Noether等式和守恒量的形式.研究Chaplygin系统的形式不变性以及它与Noether对称性的关系. 关键词： Chaplygin系统 Noether对称性 形式不变性 守恒量