13 research outputs found
Nonlinear magnetic response of the magnetized vacuum to applied electric field
We find first nonlinear correction to the field, produced by a static charge
at rest in a background constant magnetic field. It is quadratic in the charge
and purely magnetic. The third-rank polarization tensor - the nonlinear
response function - is written within the local approximation of the effective
action in an otherwise model- and approximation-independent way within any
P-invariant nonlinear electrodynamics, QED included.Comment: 11 pages without figures or tables. Numerical coefficients and some
signs in Version I corrected, three new references and two equations adde
When electric charge becomes also magnetic
In nonlinear electrodynamics, QED included, we find a static solution to the
field equations with an electric charge as its source, which is comprised of
homogeneous parallel magnetic and electric fields, and a radial
spherically-nonsymmetric long-range magnetic field, whose magnetic charge is
proportional to the electric charge and also depends on the homogeneous
component of the solution.Comment: Four pages, no figure
Path integral and pseudoclassical action for spinning particle in external electromagnetic and torsion fields
Starting from the Dirac equation in external electromagnetic and torsion
fields we derive a path integral representation for the corresponding
propagator. An effective action, which appears in the representation, is
interpreted as a pseudoclassical action for a spinning particle. It is just a
generalization of Berezin-Marinov action to the background under consideration.
Pseudoclassical equations of motion in the nonrelativistic limit reproduce
exactly the classical limit of the Pauli quantum mechanics in the same case.
Quantization of the action appears to be nontrivial due to an ordering problem,
which needs to be solved to construct operators of first-class constraints, and
to select the physical sector. Finally the quantization reproduces the Dirac
equation in the given background and, thus, justifies the interpretation of the
action.Comment: 18 pages, LaTeX. Small modifications, some references added. To be
published in International Journal of Modern Physics
Calculations of vacuum mean values of spinor field current and energy–momentum tensor in a constant electric background
In the framework of strong-field QED with x-steps, we study vacuum mean values of the current density and energy–momentum tensor of the quantized spinor field placed in the so-called L-constant electric background. The latter background can be, for example, understood as the electric field confined between capacitor plates, which are separated by a sufficiently large distance L. First, we reveal peculiarities of nonperturbative calculating of mean values in strong-field QED with x-steps in general and, in the L-constant electric field, in particular. We propose a new renormalization and volume regularization procedures that are adequate for these calculations. We find necessary representations for singular spinor functions in the background under consideration. With their help, we calculate the above mentioned vacuum means. In the obtained expressions, we show how to separate global contributions due to the particle creation and local ones due to the vacuum polarization. We demonstrate how these contributions can be related to the renormalized effective Heisenberg–Euler Lagrangian
Radiation Problems Accompanying Carrier Production by an Electric Field in the Graphene
A number of physical processes that occur in a flat one-dimensional graphene structure under the action of strong time-dependent electric fields are considered. It is assumed that the Dirac model can be applied to the graphene as a subsystem of the general system under consideration, which includes an interaction with quantized electromagnetic field. The Dirac model itself in the external electromagnetic field (in particular, the behavior of charged carriers) is treated nonperturbatively with respect to this field within the framework of strong-field QED with unstable vacuum. This treatment is combined with a kinetic description of the radiation of photons from the electron-hole plasma created from the vacuum under the action of the electric field. An interaction with quantized electromagnetic field is described perturbatively. A significant development of the kinetic equation formalism is presented. A number of specific results are derived in the course of analytical and numerical study of the equations. We believe that some of predicted effects and properties of considered processes may be verified experimentally. Among these effects, it should be noted a characteristic spectral composition anisotropy of the quantum radiation and a possible presence of even harmonics of the external field in the latter radiation