scholarly journals Вакуумное двулучепреломление в поле плоской электромагнитной волны

2021 ◽  
Vol 129 (7) ◽  
pp. 932
Author(s):  
И.А. Александров ◽  
В.М. Шабаев
Keyword(s):  
Electromagnetic Field ◽  
External Field ◽  
Field Approximation ◽  
Energy Scale ◽  
Constant Field ◽  
Polarization Tensor ◽  
Monochromatic Wave ◽  
Leading Order ◽  
Relative Uncertainty ◽  
Probe Photon

We study the process of vacuum birefringence in a strong electromagnetic field: a probe photon changes its polarization while traversing a counterpropagating laser beam. To describe this phenomenon, we calculate the polarization tensor in the field of a plane monochromatic wave to leading order with respect to its amplitude. The main goal of the study is to compare the results with the data obtained within the locally constant field approximation (LCFA). Here we identify the domain of the LCFA applicability in the case of a plane-wave external background. It is shown that the frequency of the probe photon and that of the external field are symmetrically involved in the relative uncertainty. The exact treatment of the spatiotemporal dependence beyond the LCFA becomes necessary at the energy scale 0.1-1 MeV.

scholarly journals Photon polarization tensor in circularly polarized Hermite- and Laguerre-Gaussian beams

2018 ◽  
Vol 33 (07n08) ◽  
pp. 1850044 ◽  
Author(s):  
Felix Karbstein ◽  
Elena A. Mosman
Keyword(s):  
Quantum Electrodynamics ◽  
Field Approximation ◽  
Constant Field ◽  
Polarization Tensor ◽  
Photon Polarization ◽  
Circularly Polarized ◽  
Polarized Beams ◽  
Effective Lagrangian ◽  
Linearly Polarized ◽  
The One

We derive analytical expressions for the photon polarization tensor in circularly polarized Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) beams, complementing the corresponding results for linearly polarized beams obtained recently. As they are based upon a locally constant field approximation of the one-loop Heisenberg–Euler effective Lagrangian for quantum electrodynamics (QED) in constant fields, our results are generically limited to slowly varying electromagnetic fields, varying on spatial (temporal) scales much larger than the Compton wavelength (time) of the electron.

The Einstein–Maxwell-particle system in the York canonical basis of ADM tetrad gravity. Part 2. The weak field approximation in the 3-orthogonal gauges and Hamiltonian post-minkowskian gravity: the N-body problem and gravitational waves with asymptotic background 1This paper is one of three companion papers published in the same issue of Can. J. Phys.

2012 ◽  
Vol 90 (11) ◽  
pp. 1077-1130 ◽  
Author(s):  
David Alba ◽  
Luca Lusanna
Keyword(s):  
Electromagnetic Field ◽  
Gravitational Waves ◽  
Particle System ◽  
Canonical Basis ◽  
Field Approximation ◽  
Weak Field ◽  
N Body Problem ◽  
Hamilton Equations ◽  
Weak Field Approximation ◽  
Tetrad Gravity

In this second paper we define a post-minkowskian (PM) weak field approximation leading to a linearization of the Hamilton equations of Arnowitt–Deser–Misner (ADM) tetrad gravity in the York canonical basis in a family of nonharmonic 3-orthogonal Schwinger time gauges. The York time 3K (the relativistic inertial gauge variable, not existing in newtonian gravity, parametrizing the family, and connected to the freedom in clock synchronization, i.e., to the definition of the the shape of the instantaneous 3-spaces) is set equal to an arbitrary numerical function. The matter are considered point particles, with a Grassmann regularization of self-energies, and the electromagnetic field in the radiation gauge: an ultraviolet cutoff allows a consistent linearization, which is shown to be the lowest order of a hamiltonian PM expansion. We solve the constraints and the Hamilton equations for the tidal variables and we find PM gravitational waves with asymptotic background (and the correct quadrupole emission formula) propagating on dynamically determined non-euclidean 3-spaces. The conserved ADM energy and the Grassmann regularization of self-energies imply the correct energy balance. A generalized transverse–traceless gauge can be identified and the main tools for the detection of gravitational waves are reproduced in these nonharmonic gauges. In conclusion, we get a PM solution for the gravitational field and we identify a class of PM Einstein space–times, which will be studied in more detail in a third paper together with the PM equations of motion for the particles and their post-newtonian expansion (but in the absence of the electromagnetic field). Finally we make a discussion on the gauge problem in general relativity to understand which type of experimental observations may lead to a preferred choice for the inertial gauge variable 3K in PM space–times. In the third paper we will show that this choice is connected with the problem of dark matter.

scholarly journals Derivative expansion for the one-loop effective Lagrangian in QED

1996 ◽  
Vol 74 (5-6) ◽  
pp. 282-289 ◽  
Author(s):  
V. P. Gusynin ◽  
I. A. Shovkovy
Keyword(s):  
Electromagnetic Field ◽  
Field Strength ◽  
External Field ◽  
Explicit Expression ◽  
Derivative Expansion ◽  
Effective Lagrangian ◽  
Constant Electromagnetic Field ◽  
The One ◽  
Derivatives Of

The derivative expansion of the one-loop effective Lagrangian in QED4 is considered. The first term in such an expansion is the famous Schwinger result for a constant electromagnetic field. In this paper we give an explicit expression for the next term containing two derivatives of the field strength Fμν. The results are presented for both fermion and scalar electrodynamics. Some possible applications of an inhomogeneous external field are pointed out.

scholarly journals Improved local-constant-field approximation for strong-field QED codes

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
A. Di Piazza ◽  
M. Tamburini ◽  
S. Meuren ◽  
C. H. Keitel
Keyword(s):  
Strong Field ◽  
Field Approximation ◽  
Constant Field

Resonant production of electron-positron pairs by a hard gamma-ray on a nucleus in an external electromagnetic field

2020 ◽  
Vol 35 (03) ◽  
pp. 2040025 ◽  
Author(s):  
Nikita R. Larin ◽  
Victor V. Dubov ◽  
Sergei P. Roshchupkin
Keyword(s):  
Electromagnetic Field ◽  
Differential Cross Section ◽  
External Field ◽  
Cross Section ◽  
Differential Cross ◽  
Gamma Ray ◽  
Structure Constant ◽  
External Electromagnetic Field ◽  
Electron Positron ◽  
Resonant Production

The resonant production of electron-positron pairs by a hard gamma-ray on nucleus in an external electromagnetic field is studied theoretically. The main property of this process is that the initial process of the second order in the fine structure constant in an external field effectively splits into two successive processes of the first order due to the fact that in resonant conditions intermediate virtual electron (positron) becomes a real particle. One of these processes is a single-photoproduction of electron-positron pair in a laser field (laser-stimulated Breit-Wheeler process) another is a laser-assisted scattering of electron (positron) on nucleus (laser-assisted Mott scattering). It is shown that the resonances are possible only for the energies of the initial hard gamma-ray more than the characteristic threshold energy. Resonant differential cross section of this process is obtained. It is shown that the resonant differential cross section can significantly exceed the corresponding cross section without an external field. The obtained results may be experimentally verified using the facilities of pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS).

QUANTUM FLUCTUATIONS ENHANCE SUPERFLUIDITY IN TWO-DIMENSIONAL WEAKLY INTERACTING BOSON SYSTEM

2012 ◽  
Vol 26 (17) ◽  
pp. 1250107 ◽  
Author(s):  
PEI-SONG HE ◽  
WEN-LONG YOU
Keyword(s):  
Renormalization Group ◽  
Chemical Potential ◽  
Field Approximation ◽  
High Energy ◽  
Superfluid Density ◽  
Energy Scale ◽  
Mean Field Approximation ◽  
Two Dimensional ◽  
Boson System ◽  
Weakly Interacting

In the present paper, we compute the superfluid density of two-dimensional weakly interacting boson system at zero temperature using one-loop renormalization group calculations under the scheme of newly derived formula [M. Holzmann and G. Baym Phy. Rev. B 76, 092502 (2007)]. We find that the interactions between the boson particles are marginally irrelevant in the renormalization group sense. The fluctuations of high-energy scale enhance superfluid density compared with the result of the mean-field approximation. The correction has ( ln μ) form, where μ is the chemical potential of the boson system.

Local electric fields and molecular properties in heterogeneous environments through polarizable embedding

2016 ◽  
Vol 18 (15) ◽  
pp. 10070-10080 ◽  
Author(s):  
Nanna Holmgaard List ◽  
Hans Jørgen Aagaard Jensen ◽  
Jacob Kongsted
Keyword(s):  
Electromagnetic Field ◽  
External Field ◽  
Electric Fields ◽  
Molecular Properties ◽  
Heterogeneous Environments ◽  
Field Effects ◽  
Polarizable Embedding

Effective external field effects in spectroscopies of molecules in heterogeneous environments, i.e., the implications of the additional environment polarization induced by the probing electromagnetic field, can be significant and depart remarkably from the simple Onsager picture.

scholarly journals A thermodynamic description for physiological transmembrane transport

F1000Research ◽  
2021 ◽  
Vol 7 ◽  
pp. 1468
Author(s):  
Marco Arieli Herrera-Valdez
Keyword(s):  
Common Ground ◽  
Transmembrane Potential ◽  
Thermodynamic Description ◽  
Field Approximation ◽  
Transmembrane Transport ◽  
Constant Field ◽  
Asymmetric Flow ◽  
Biophysical Study ◽  
Transmembrane Currents ◽  
Existing Data

A general formulation for both passive and active transmembrane transport is derived from basic thermodynamical principles. The derivation takes into account the energy required for the motion of molecules across membranes and includes the possibility of modeling asymmetric flow. Transmembrane currents can then be described by the general model in the case of electrogenic flow. As it is desirable in new models, it is possible to derive other well-known expressions for transmembrane currents as particular cases of the general formulation. For instance, the conductance-based formulation for current turns out to be a linear approximation of the general formula for current. Also, under suitable assumptions, other formulas for current based on electrodiffusion, like the constant field approximation by Goldman, can be recovered from the general formulation. The applicability of the general formulations is illustrated first with fits to existing data, and after, with models of transmembrane potential dynamics for pacemaking cardiocytes and neurons. The general formulations presented here provide a common ground for the biophysical study of physiological phenomena that depend on transmembrane transport.

scholarly journals Structured objects in quantum gravity. The external field approximation

2018 ◽  
Vol 27 (09) ◽  
pp. 1850104 ◽  
Author(s):  
Giorgio Papini
Keyword(s):  
External Field ◽  
Symmetry Breaking ◽  
Field Approximation ◽  
Metric Tensor ◽  
Interaction Range ◽  
Vortical Structures ◽  
Scalar Particles ◽  
Structured Objects ◽  
Classical Gravity ◽  
Point Vector

The external field approximation (EFA) provides a mechanism whereby classical gravity and inertia emerge from a quantum background. The two-point vector, that in EFA represents gravity, is the byproduct of symmetry breaking and is accompanied by classical, vortical structures. Its interaction range is, in general, that of the metric tensor, but, in the context of a simple symmetry-breaking model, the range can be made finite by the presence of massive scalar particles. Vortices that conceal matter can then be produced, making it effectively “dark”. In EFA, fermion relativistic vortices can be induced, in particular, by rotation.

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