On the choice of evolutional parameter within a framework of four-dimensional symmetry

Within the context of the variational principle, there is the freedom to choose specific evolutional parameters. Different parameters can be associated with physical time, while allowing the physical laws to preserve the property of four-dimensional symmetry. In this sense, the concept of time has flexibility. Besides proper time and relativistic time, another natural choice emerges, which is called the generalized Galilean time. We study the impact of this choice here. This approach provides a deeper understanding of the theory of special relativity, and it also provides a new basis to study other space-time theories.On leave from Shanghai University of Science and Technology, Shanghai, China.     

Common time in a four-dimensional symmetry framework

Following the ideas of Poincaré, Reichenbach, and Grunbaum concerning the convention of setting up clock systems, we analyze clock systems and light propagation within the framework of four-dimensional symmetry. It is possible to construct a new four-dimensional symmetry framework incorporatingcommon time: observers in different inertial frames of reference use one and the same clock system, which is located in any one of the frames. Consequently, simultaneity has a meaning independent of position and independent of frame of reference. A further consequence is that the two-way speeds of light alone are isotropic in any frame. By the choice of clock system there will be one frame in which the one-way speed of light is isotropic. This frame can be arbitrarily chosen. The difference between one-way speeds and two-way speeds of light signals is considered in detail.Work supported by the NRC, NASA, and the U.S. DOE.     

Quantum electrodynamics on a space-time lattice

A Minkowski-lattice version of quantum electrodynamics (or rather its simplified version, with matter described by a scalar field) is constructed. Quantum fields are consequently described in a gauge-independent way, i.e. the algebra of quantum observables of the theory is generated by gauge-invariant operators assigned to zero-, one-, and two-dimensional elements of the lattice. The operators satisfy canonical commutation relations. The uniqueness of representation of this algebra is proved. Field dynamics is formulated in terms of difference equations imposed on the field operators. It is obtained from a discrete version of the path-integral. The theory is local and causal.     

Gravidynamics,spinodynamics and electrodynamics within the framework of gravitational quantum field theory

By noticing the fact that the charged leptons and quarks in the standard model are chirality-based Dirac spinors since their weak interaction violates maximally parity symmetry though they behave as Dirac fermions in electromagnetic interaction, we show that such a chirality-based Dirac spinor possesses not only electric charge gauge symmetry U(1) but also inhomogeneous spin gauge symmetry WS(1,3)=SP(1,3)?W^1,3, which reveals the nature of gravity and spacetime. The gravitational force...     

A discrete geometry: Speculations on a new framework for classical electrodynamics

An attempt is made to describe the basic principles of physics in terms of discrete partially ordered sets. Geometric ideas are introduced by means of an action at a distance formulation of classical electrodynamics. The speculations are in two main directions: (i) Gravity, one of the four elementary forces of nature, seems to be fundamentally different from the other three forces. Could it be that gravity can be explained as a natural consequence of the discrete structure? (ii) The problem of the observer in quantum mechanics continues to cause conceptual problems. Can quantum statistics be explained in terms of finite ensembles of possible partially ordered sets? The development is guided at all stages by reference to the simplest, and most well-established principles of physics.     

Quantum electrodynamics in the temporal gauge

We canonically quantize electrodynamics in the temporal gauge A₀ = 0. Realizing commutation relations in a Hilbert space containing unphysical longitudinal photons, we pay special attention to the implementation of Gauss's law and the attendant normalization difficulties for physical states. We then formulate the perturbation series and explicitly exhibit equivalence with the standard textbook treatment of the Coulomb gauge.     

Quantum electrodynamics as a supersymmetric theory of Loops

It is shown that the Wilson loop is not a renormalizable operator even in free QED. A modification is suggested and proven to be renormalizable. Feynman's worldline formulation of QED is generalized to include spinning particles and matter loops, using this modified Wilson loop. QED formulated this way is shown to have a supersymmetry. A superfield formalism is found that describes it. QED is rewritten as a second quantized field theory of loop functionals.     

Phase transitions in four-dimensional AdS black holes with a nonlinear electrodynamics source

In this work we consider black hole solutions to Einstein's theory coupled to a nonlinear power-law electromagnetic field with a fixed exponent value. We study the extended phase space thermodynamics in canonical and grand canonical ensembles, where the varying cosmological constant plays the role of an effective thermodynamic pressure. We examine thermodynamical phase transitions in such black holes and find that both first- and second-order phase transitions can occur in the canonical ensemble while, for the grand canonical ensemble, Hawking–Page and second-order phase transitions are allowed.     

Quantum electrodynamics resonances in a pulsed laser field

This review contains theoretical study of resonant quantum electrodynamics processes in a pulsed laser field. The approximation is examined when the pulse width is considerably greater than the characteristic time of wave oscillations. The lepton??s interaction with the Coulomb potential of a nucleus and each other is considered in the Born approximation. It is demonstrated that the resonant differential cross section of a process in a pulsed light fields may considerably exceed the corresponding cross section in an absence of a laser field. Results obtained may be experimentally verified by the scientific facilities at the SLAC National Accelerator Laboratory and FAIR (Facility for Antiproton and Ion Research, Darmstadt, Germany) project.     

Sign inversion for the velocity of light — A new discrete symmetry transform in electrodynamics

The invariance of the electrodynamic equations with respect to change in sign of the velocity of light is shown. Some physical consequences of this symmetry are considered.I. V. Kurchatov Institute of Atomic Energy. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 69–72, December, 1992.     

Quantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron– laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of γ-ray laser generation by use of this kind of collision is discussed.     

Quantum electrodynamics of weakly bound systems

An overview of quantum electrodynamic effects in two-body systems is presented. Recent advances in the calculation of the hydrogen Lamb shift, muonium hyperfine structure, and positronium energy levels are described in detail. The comparison of experimental results to current theoretical predictions gives agreement in most cases. However, a few significant discrepancies remain, which indicates the necessity for further refined calculations and measurements. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantum electrodynamics of one scalar particle

The theory of the interaction between a complex scalar field and the electromagnetic field is presented with initial and final conditions that allow an interpretation in the context of the relativistic quantum mechanics of a single charged scalar particle. Included are particle scattering, antiparticle scattering, pair creation, and pair annihilation due to a classical dynamical electromagnetic field. The equations of motion are solved by a perturbation expansion, which does not lead to the troublesome divergent terms of quantum field theory.     

Quantum electrodynamics in a laser and the electron laser collisionQuantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron-laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron- laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of y-ray laser generation by use of this kind of collision is discussed.     

Quantum electrodynamics with arbitrary charge on a noncommutative space

Using the Seiberg-Witten map,we obtain a quantum electrodynamics on a noncommutative space,which has arbitrary charge and keep the gauge invariance to at the leading order in theta.The one-loop divergence and Compton scattering are reinvestigated.The uoncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics.     

Galilean symmetry of Maxwell's equations in classical electrodynamics

It is shown that the Galilean group, like the Lorentz group, is a group of exact symmetry of Maxwell's equation. The Galilean group differs in that, while the field transformations are linear and global in the relativistic case, they are nonlinear in the Galilean and, generally speaking, depend on the coordinates of the event through some weight functions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 78–83, August, 1985.The author thanks D. P. Grechukhin, V. I. Man'ko, and V. I. Fushchich for discussion of the work and valuable comments.     

Quantum electrodynamics with arbitrary charge on a noncommutative space

Using the Seiberg-Witten map, we obtain a quantum electrodynamics on a noncommutative space, which has arbitrary charge and keep the gauge invariance to at the leading order in theta. The one-loop divergence and Compton scattering are reinvestigated. The noncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics.     

Effect of tensor force on the density dependence of symmetry energy within the BHF framework

The effect of tensor force on the density dependence of nuclear symmetry energy has been investigated within the framework of the Brueckner-Hartree-Fock(BHF) approach. It is shown that the tensor force manifests its effect via the tensor 3 S D1channel. The density dependence of symmetry energy Esym turns out to be determined essentially by the tensor force from the π meson and ρ meson exchanges via the 3 S D1 coupled channel. Increasing the strength of the tensor component due to the ρ-meson exchange tends to enhance the repulsion of the equation of state of symmetric nuclear matter and leads to the reduction of symmetry energy. The present results confirm the dominant role played by the tensor force in determining nuclear symmetry energy and its density dependence within the microscopic BHF framework.