scholarly journals OPTICAL PROBES OF THE QUANTUM VACUUM: THE PHOTON POLARIZATION TENSOR IN EXTERNAL FIELDS

2012 ◽  
Vol 14 ◽  
pp. 403-415 ◽  
Author(s):  
FELIX KARBSTEIN ◽  
LARS ROESSLER ◽  
BABETTE DÖBRICH ◽  
HOLGER GIES
Keyword(s):  
Electromagnetic Fields ◽  
Effective Theory ◽  
Constant Field ◽  
Momentum Dependence ◽  
Polarization Tensor ◽  
Quantum Vacuum ◽  
Vacuum Fluctuations ◽  
Photon Polarization ◽  
Photon Propagation ◽  
External Electromagnetic Fields

The photon polarization tensor is the central building block of an effective theory description of photon propagation in the quantum vacuum. It accounts for the vacuum fluctuations of the underlying theory, and in the presence of external electromagnetic fields, gives rise to such striking phenomena as vacuum birefringence and dichroism. Standard approximations of the polarization tensor are often restricted to on-the-light-cone dynamics in homogeneous electromagnetic fields, and are limited to certain momentum regimes only. We devise two different strategies to go beyond these limitations: First, we aim at obtaining novel analytical insights into the photon polarization tensor for homogeneous fields, while retaining its full momentum dependence. Second, we employ wordline numerical methods to surpass the constant-field limit.

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.

scholarly journals Dipole radiation and beyond from axion stars in electromagnetic fields

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Mustafa A. Amin ◽  
Andrew J. Long ◽  
Zong-Gang Mou ◽  
Paul M. Saffin
Keyword(s):  
Electromagnetic Fields ◽  
Parametric Resonance ◽  
Coupling Strength ◽  
Coupling Parameter ◽  
Strong Dependence ◽  
Dipole Radiation ◽  
Large Coupling ◽  
External Electromagnetic Fields ◽  
Order Of Magnitude ◽  
Dimensionless Coupling

Abstract We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the photon luminosity in terms of an effective dimensionless coupling parameter constructed out of the axion-photon coupling, and field amplitude, oscillation frequency and radius of the axion star. For small values of this dimensionless coupling, we provide a general analytic formula for the dipole radiation field and the photon luminosity per solid angle, including a strong dependence on the radius of the configuration. For moderate to large coupling, we report on a non-monotonic behavior of the luminosity with the coupling strength in the presence of external magnetic fields. After an initial rise in luminosity with the coupling strength, we see a suppression (by an order of magnitude or more compared to the dipole radiation approximation) at moderately large coupling. At sufficiently large coupling, we find a transition to a regime of exponential growth of the luminosity due to parametric resonance. We carry out 3+1 dimensional lattice simulations of axion electrodynamics, at small and large coupling, including non-perturbative effects of parametric resonance as well as backreaction effects when necessary. We also discuss medium (plasma) effects that lead to resonant axion to photon conversion, relevance of the coherence of the soliton, and implications of our results in astrophysical and cosmological settings.

scholarly journals TEMPERATURE OF ELECTRON FLUCTUATIONS IN AN ACCELERATED VACUUM

2013 ◽  
Vol 28 (03) ◽  
pp. 1340015 ◽  
Author(s):  
LANCE LABUN ◽  
JOHANN RAFELSKI
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
State Density ◽  
Gyromagnetic Ratio ◽  
Constant Field ◽  
Vacuum Fluctuations ◽  
Spectral State

The electron vacuum fluctuations measured by [Formula: see text] do not vanish in an externally applied electric field ℰ. For an exactly constant field, that is for vacuum fluctuations in presence of a constant accelerating force, we show that [Formula: see text] has a Boson-like structure with spectral state density tanh -1(E/m) and temperature T M = eℰ/mπ = av/π. Considering the vacuum fluctuations of 'classical' gyromagnetic ratio g = 1 particles we find Fermi-like structure with the same spectral state density at a smaller temperature T1 = av/2π which corresponds to the Unruh temperature of an accelerated observer.

scholarly journals Classical enhancement of quantum vacuum fluctuations

2017 ◽  
Vol 95 (1) ◽  
Author(s):  
V. A. De Lorenci ◽  
L. H. Ford
Keyword(s):  
Quantum Vacuum ◽  
Vacuum Fluctuations

scholarly journals Quantum Vacuum Fluctuations in a Chromomagnetic-Like Background

2018 ◽  
Vol 48 (6) ◽  
pp. 645-651
Author(s):  
V. B. Bezerra ◽  
M. S. Cunha ◽  
C. R. Muniz ◽  
M. O. Tahim
Keyword(s):  
Quantum Vacuum ◽  
Vacuum Fluctuations
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