Massive Electrodynamics and Magnetic Monopoles

Including torsion in the geometric framework of the Weyl-Dirac theory we build up an action integral, and obtain from it a gauge covariant (in the Weyl sense) general relativistic massive electrodynamics. Photons having an arbitrary mass, electric, and magnetic currents (Dirac's monopole) coexist within this theory. Assuming that the space-time is torsionless, taking the photon mass zero, and turning to the Einstein gauge we obtain Maxwell's electrodynamics.     

Magnetic Monopoles and Massive Photons in a Weyl-Type Electrodynamics

In a previous work the Weyl-Dirac framework was generalized in order to obtain a geometrically based general relativistic theory, possessing intrinsic electric and magnetic currents and admitting massive photons. Some physical phenomena in that framework are considered. It is shown that massive photons may exist only in the presence of an intrinsic magnetic field. The role of massive photons is essential in order to get an interaction between magnetic currents. A static spherically symmetric solution is obtained. It may lead either to the Reissner-Nordström metric, or to the metric created by a magnetic monopole.     

Vacuum Effects on Massive Spinor Fields: S 1× R 3 Topology

The aim of this work was to investigate the role played by an external field on the Casimir energy density for massive fermions under S ¹× R ³ topology. Both twisted- and untwisted-spin connections are considered and the calculation in a closed form is performed using an alternative approach based on the combination of the analytic regularization method and the Euler–Maclaurin summation formula. It is shown that no mass scale appears in the final result and, therefore, Casimir effect arises only from the boundary conditions and vacuum fluctuations induced by the coupling with the external field. PACS numbers: 11.10.Wx     

关于磁单极子的探索

磁单极子的概念自狄拉克提出以来,科学家一直都在努力寻找。虽然在理论上进行了深入的研究,但是在实验中,迄今仍然没能找到它们存在的确凿证据。文章从麦克斯韦方程组的对称性及电荷量子化的角度介绍了磁单极子的提出,磁单极子的单位及性质。并介绍了关于磁单极子的实验探索,除了历史上著名的两次实验外,科学家还在自旋冰中观察到磁单极子的“准粒子”。     

Plane-Symmetric Solitons of Spinor and Scalar Fields

We consider a system of nonlinear spinor and scalar fields with minimal coupling in general relativity. The nonlinearity in the spinor field Lagrangian is given by an arbitrary function of the invariants generated from the bilinear spinor forms S= and P=i⁵; the scalar Lagrangian is chosen as an arbitrary function of the scalar invariant = _,^,, that becomes linear at 0. The spinor and the scalar fields in question interact with each other by means of a gravitational field which is given by a plane-symmetric metric. Exact plane-symmetric solutions to the gravitational, spinor and scalar field equations have been obtained. Role of gravitational field in the formation of the field configurations with limited total energy, spin and charge has been investigated. Influence of the change of the sign of energy density of the spinor and scalar fields on the properties of the configurations obtained has been examined. It has been established that under the change of the sign of the scalar field energy density the system in question can be realized physically iff the scalar charge does not exceed some critical value. In case of spinor field no such restriction on its parameter occurs. In general it has been shown that the choice of spinor field nonlinearity can lead to the elimination of scalar field contribution to the metric functions, but leaving its contribution to the total energy unaltered.     

Interaction of $F=2$ Spinor Bose Condensate with Driven External Magnetic Fields

We have studied the interaction of $F=2$ spinor Bose condensate with a combination of static and sinusoidal magnetic field $b_l(t)=b_0+b\cos(\omega t)$. We find that the tunneling current among spin 0 and spin $\pm1$, spin 0 and spin $\pm2$, spin $\pm1$ and spin $\pm2$ may exhibit the incremental oscillation behavior, which depends on the field parameters of the reduced amplitudes of the transverse and the longitudinal magnetic fields respectively. This means that the dynamics spin localization can be adjusted experimentally by selecting the less values of the reduced amplitudes of the transverse magnetic field $b_x/\omega$ and those of the longitudinal magnetic field $b/\omega$.     

Magnetic Monopoles and the Orientation Entanglement Relation

We show that Dirac magnetic monopoles do not satisfy the orientationentanglement (OE) relation and do not return to their initial state after a 4rotation. This is done in both the formalism using Dirac strings of singularitiesand in the fiber bundle formalism. In the latter we connect the OE relation tothe first homotopy group of the gauge group. We hypothesize that failure tosatisfy the OE relation is the reason Dirac magnetic monopoles have neverbeen seen.     

Nonlinear Spinor Fields in Bianchi type-III Spacetime

Within the scope of Bianchi type-III spacetime we study the role of spinor field on the evolution of the Universe as well as the influence of gravity on the spinor field. In doing so we have considered a polynomial type of nonlinearity. In this case the spacetime remains locally rotationally symmetric and anisotropic all the time. It is found that depending on the sign of nonlinearity the models allows both accelerated and oscillatory modes of expansion. The non-diagonal components of energy-momentum tensor though impose some restrictions on metric functions and components of spinor field, unlike Bianchi type I, V and V I ₀ cases, they do not lead to vanishing mass and nonlinear terms of the spinor field.     

Self-Gravitating String-Like Configurations of Nonlinear Spinor Fields

We consider the problem of the existence of soliton-like self-gravitating cylindrically symmetric configurations of a classical spinor field with the nonlinearity F(S) ( , F is an arbitrary function). Soliton-like configurations should have, by definition, a regular axis of symmetry and a flat or string-like geometry far from the axis (i.e., an asymptotically Minkowskian metric with a possible angular defect). It is shown that these conditions can be fulfilled if F(S) is finite as S and decreases faster than S ² as S 0. The set of field equations is entirely integrated, and some explicit examples are considered. A regularizing role of gravity is discussed.     

Some Comments on Quantum Magnetic Monopoles

In this paper we intend to present some path-integral studies in the problem of confinement in the presence of fermionic and scalar magnetic monopole fields through:

Electric and Magnetic Monopoles from a Lorentz-Covariant Hamiltonian

In previous work we generalized the relation between the usual noncovariantHamiltonian and the Poisson brackets to a covariant Hamiltonian and new bracketsin the frame of Minkowski space. In the present paper we study the consequencesof this new algebraic structure on the Lorentz Lie algebra defined in terms ofthese brackets. We show how a monopole with a dual electric—magnetic chargeappears as a consequence of the conservation of the form of the standard Lorentzalgebra symmetry. The breakdown of this symmetry is also envisaged.     

Direct and Indirect Searches for Low-Mass Magnetic Monopoles

Recently, there has been renewed interest in the search for low-mass magnetic monopoles. At the University of Oklahoma we are performing an experiment (Fermilab E882) using material from the old D0 and CDF detectors to set limits on the existence of Dirac monopoles of masses of the order of 500 GeV. To set such limits, estimates must be made of the production rate of such monopoles at the Tevatron collider, and of the binding strength of any such produced monopoles to matter. Here we sketch the still primitive theory of such interactions, and indicate why we believe a credible limit may still be obtained. On the other hand, there have been proposals that the classic Euler–Heisenberg Lagrangian together with duality could be employed to set limits on magnetic monopoles having masses less than 1 TeV, based on virtual, rather than real processes. The D0 collaboration at Fermilab has used such a proposal to set mass limits based on the nonobservation of pairs of photons each with high transverse momentum. We critique the underlying theory, by showing that the cross section violates unitarity at the quoted limits and is unstable with respect to radiative corrections. We therefore believe that no significant limit can be obtained from the current experiments, based on virtual monopole processes.     

Spinor Representation of Electromagnetic Fields on Noncommutative Spaces

We apply Campolattaro's spinor representation of the electromagnetic field to noncommutative spaces. The spinor representation of the (self-dual) electromagnetic field on noncommutative spaces is obtained.     

Static Plane-Symmetric Nonlinear Spinor and Scalar Fields in GR

We consider a system of minimally coupled nonlinear spinor and scalar fields within the scope of a plane-symmetric gravitational field. The gravitational field plays crucial role in the formation of soliton-like solutions, i.e., solutions with limited total energy, spin, and charge. The change of the sign of the scalar field energy density of the system in question realizes physically if and only if the scalar charge does not exceed some critical value. In case of spinor field no such restriction on its parameter occurs. The choice of spinor field nonlinearity leads to the elimination of scalar field contribution to the metric functions, but leaves its contribution to the total energy unaltered. The spinor field is more sensitive to the gravitational field than the scalar field.