Electron-Positron Vacuum Instability in Strong Electric Fields. Relativistic Semiclassical Approach

The instability of electron-positron vacuum in strong electric fields is studied. First, falling to the Coulomb center is discussed at Z>137/2 for a spinless boson and at Z>137 for electron. Subsequently, focus is concentrated on description of deep electron levels and spontaneous positron production in the field of a finite-size nucleus with the charge Z>Zcr≃170. Next, these effects are studied in application to the low-energy heavy-ion collisions. Subsequently, we consider phenomenon of “electron condensation” on levels of upper continuum crossed the boundary of the lower continuum ϵ=−m in the field of a supercharged nucleus with Z≫Zcr. Finally, attention is focused on many-particle problems of polarization of the quantum electrodynamics (QED) vacuum and electron condensation at ultra-short distances from a source of charge. We argue for a principal difference of cases, when the size of the source is larger than the pole size rpole, at which the dielectric permittivity of the vacuum reaches zero and smaller rpole. Some arguments are presented in favor of the logical consistency of QED. All of the problems are considered within the same relativistic semiclassical approach.

UNIVERSAL DIAMAGNETISM: EXACT RESULTS AND APPLICATIONS

Diamagnetism is a universal pheneomenon of spinless boson system at any finite temperature regardless of their interactions. We present here the exact, non-perturbative results of universal diamagnetism of charged scalar fields at any finite temperature. As an application, we study the effect of anisotropy of two coherence lengths on diamagnetic susceptibility of Cooper pairs in an arbitrary d-dimensions above the transition temperature.