Abstract
In this paper we show how to recast the results of the semiclassical method of Baier, Katkov & Strakhovenko for pair production, including the possibility of specifying all the spin states and photon polarization, in a form that is suitable for numerical implementation. In this case, a new type of integral appears in addition to the ones required for the radiation emission process. We compare the resulting formulas with those obtained for a short pulse plane wave external field by using the Volkov state. We investigate the applicability of the local constant field approximation for the proposed upcoming experiments at FACET II at SLAC and LUXE at DESY. Finally, we provide results on the dependence of the pair production rate on the relative polarization between a linearly polarized laser pulse and a linearly polarized incoming high energy photon. We observe that even in the somewhat intermediate intensity regime of these experiments, there is roughly a factor of $2$ difference between the pair production rates corresponding to the two relative photon polarizations, which is of interest in light of the vacuum birefringence of QED.
Highlights
In view of the rapid development of laser technology, the consideration of nonlinear QED effects in the interaction of light with matter is increasingly important
In particular we show how the semiclassical method of Baier, Katkov and Strakhovenko [44,45] in its most general form, including spins and polarizations, can be recast into a form that is suitable for numerical implementation
We have shown how the semiclassical approach of Baier, Katkov and Strakhovenko may be recast in a form suitable for numerical implementation, allowing one to calculate the pair production probability in an arbitrary external field and for any photon polarization and electron-positron spins
Summary
In view of the rapid development of laser technology, the consideration of nonlinear QED effects in the interaction of light with matter is increasingly important. Future experiments at SLAC, DESY and the Extreme Light Infrastructure, aim to study these processes further into the nonlinear regime [28,29,30,31] Another related nonlinear process of strong-field QED is that of electron-positron pair production, for the case of a laser field, called the nonlinear Breit-Wheeler process. In particular we show how the semiclassical method of Baier, Katkov and Strakhovenko [44,45] in its most general form, including spins and polarizations, can be recast into a form that is suitable for numerical implementation The strength of this approach is that it can be used in any background field, as only the Lorentz force trajectory of the produced electron in this field is required, which is found numerically. We will use units where ħ 1⁄4 c 1⁄4 1, and e is the elementary charge (e2 ∼ 1=137)
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