The exact solutions of the equation for a composite particle in the external electromagnetic fields

1994 ◽  
Vol 35 (9) ◽  
pp. 4497-4504 ◽  
Author(s):  
Jing‐fa Lu ◽  
S. I. Kruglov
Keyword(s):  
Exact Solutions ◽  
Electromagnetic Fields ◽  
Composite Particle ◽  
External Electromagnetic Fields

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.

Influence of External Electromagnetic Fields on the Structure of Joints in the Course of Underwater Welding

2021 ◽  
Author(s):  
O. M. Berdnikova ◽  
S. Yu. Maksimov ◽  
O. O. Prilipko ◽  
T. O. Alekseienko ◽  
E. V. Polovetskyi ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Underwater Welding ◽  
External Electromagnetic Fields
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