Abstract
The Dirac-Heisenberg-Wigner formalism is employed to investigate electron-positron pair production in cylindrically symmetric but otherwise spatially inhomogeneous, oscillating electric fields. The oscillation frequencies are hereby tuned to obtain multiphoton pair production in the nonperturbative threshold regime. An effective mass as well as a trajectory-based semi-classical analysis are introduced in order to interpret the numerical results for the distribution functions as well as for the particle yields and spectra. The results, including the asymptotic particle spectra, display clear signatures of ponderomotive forces.
Highlights
Electron-positron pair production in strong electric fields, the Sauter-Schwinger effect, is a long-standing theoretical prediction [1] which still awaits experimental verification
The dynamically assisted Sauter-Schwinger effect [3,4] exploits the idea that a combination of a low with a high frequency (“multiphoton”) laser pulse will lead to pair production rates which are significantly larger than the sum of the rates for the two separate pulses
We have presented numerical solutions describing multiphoton pair production for oscillating, spatially inhomogeneous electric fields in the DHW formalism
Summary
Electron-positron pair production in strong electric fields, the Sauter-Schwinger effect, is a long-standing theoretical prediction [1] which still awaits experimental verification. One possibility to quantify the effects associated with a spatially inhomogeneous field is based on the notion of an effective mass which an electron acquires in a background electromagnetic field [12,13,14,15,16,17,18] This parameter, as every effective mass, reflects the “integrated” collective interactions of a particle with its surroundings. It provides the possibility of a drastic simplification but allows the coarse-grained description of highly intricate effects This might be an oversimplification with respect to details of the resulting spectra, the concept of an effective mass works astonishingly well, a fact which can be attributed to the unique conditions in high-intensity laser experiments [19]. In the following we will discuss particle creation in inhomogeneous fields and introduce, to this end, a more general concept for the effective mass and relate it via a semiclassical analysis to ponderomotive forces. We use ħ 1⁄4 c 1⁄4 1 throughout this paper
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