Title: Electron-positron bremsstrahlung and pair creation in very high magnetic fields Authors: P B Jones

Cross-sections for Rutherford scattering, Coulomb bremsstrahlung and pair creation, have been calculated at very high magnetic fields in order to investigate the photo-production of protons at the polar caps of pulsars whose spin is antiparallel with the polar magnetic flux density. The Landau-Pomeranchuk-Migdal effect at very high magnetic fields is included in a simple electron Green function.

Title: Electron-positron pair oscillation in spatially inhomogeneous electric fields and radiation Authors: Wen-Biao Han, Remo Ruffini, She-Sheng Xue (Version v2)

It is known that strong electric fields produce electron and positron pairs from the vacuum, and due to the back-reaction these pairs oscillate back and forth coherently with the alternating electric fields in time. We study this phenomenon in spatially inhomogeneous and bound electric fields by integrating the equations of energy momentum and particle-number conservations and Maxwell equations. The space and time evolutions of the pair-induced electric field, electric charge- and current densities are calculated. The results show that non-vanishing electric charge-density and the propagation of pair-induced electric fields, differently from the case of homogeneous and unbound electric fields. The space and time variations of pair-induced electric charges and currents emit an electromagnetic radiation. We obtain the narrow spectrum and intensity of this radiation, whose peak {\omega}peak locates in the region around 4 KeV for electric field strength \sim Ec. We discuss their relevance to both the laboratory experiments for electron and positron pair-productions and the astrophysical observations of compact stars with an electromagnetic structure.

Title: Electron-Positron Pair Production in Space- or Time-Dependent Electric Fields Authors: Hagen Kleinert, Remo Ruffini, She-Sheng Xue

Treating the production of electron and positron pairs by a strong electric field from the vacuum as a quantum tunnelling process we derive, in semiclassical approximation, a general expression for the pair production rate in a z-dependent electric field E(z) pointing in the z-direction. We also allow for a smoothly varying magnetic field parallel to E(z). The result is applied to a confined field E(z)\not=0 for |z| <~ \ell , a semi-confined field E(z)\not=0 for z >~ 0 , and a linearly increasing field E(z) ~ z. The boundary effects of the confined fields on pair-production rates are exhibited. A simple variable change in all formulas leads to results for electric fields depending on time rather than space. In addition, we discuss tunnelling processes in which empty atomic bound states are spontaneously filled by negative-energy electrons from the vacuum under positron emission. In particular, we calculate the rate at which the atomic levels of a bare nucleus of finite size r_{ m n} and large Z\gg 1 are filled by spontaneous pair creation.