Abstract
We investigate the phenomenon of electron-positron pair production from vacuum in the presence of a strong electric field superimposed by a weak but fast varying pulse which substantially increases the total particle yield. We employ a nonperturbative numerical technique and perform the calculations beyond the spatially-uniform-field approximation, i.e. dipole approximation, taking into account the coordinate dependence of the fast component. The analysis of the main characteristics of the pair-production process (momentum spectra of particles and total amount of pairs) reveals a number of important features which are absent within the previously used approximation. In particular, the structure of the momentum distribution is modified both qualitatively and quantitatively, and the total number of pairs created as well as the enhancement factor due to dynamical assistance become significantly smaller.
Highlights
The process of the vacuum decay accompanied by the production of electron-positron pairs in the presence of strong external fields was predicted decades ago [1,2,3] and still remains a very intriguing phenomenon
We examined the main characteristics of the dynamically assisted Schwinger effect going beyond the previously used dipole approximation
We summarize our main findings below: (1) The structure of the momentum spectra of particles created becomes significantly different beyond the dipole approximation
Summary
The process of the vacuum decay accompanied by the production of electron-positron pairs in the presence of strong external fields was predicted decades ago [1,2,3] and still remains a very intriguing phenomenon. It turns out that the combination of these two pulses can lead to a dramatic enhancement of the particle yield This phenomenon was first studied in Ref. In this study we consider a combination of a uniform time-dependent strong field and a standing wave containing rapid oscillations in space and time After completion of the present investigation we noticed the very recent study [16], where it was demonstrated that the spatial dependence of the external field plays a crucial role in the context of the Breit-Wheeler process, where a combination of two fast-varying laser pulses is considered. Relativistic units (ħ 1⁄4 1, c 1⁄4 1) are employed throughout the paper
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