Numerical approach to the semiclassical method of pair production for arbitrary spins and photon polarization

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.

Electron spin- and photon polarization-resolved probabilities of strong-field QED processes

“…Especially simple analytical expressions for the amplitude are obtained in the ultrarelativistic regime, applying the 1/γ-expansion up to the leading order, which provides the process description within the LCFA. Recently, the semiclassical QED operator method beyond LCFA has been applied numerically to investigate the polarization effects in laser fields of moderate intensity [74], where the calculation of radiation spectra was carried out with numerical integrations using the electron exact classical trajectories.…”

Photon polarization effects in polarized electron-positron pair production in a strong laser field

“…Recently, the QED Monte Carlo method has been generalized to include spin of involved leptons 24,32 and polarization of emitted or absorbed photons 13,25,34,51 . A numerical approach suitable for treating polarization effects beyond LCFA and plane wave approximations at intermediate laser intensities has been developed 52,53 for strong-field pair production process within the semiclassical formalism of Baier-Katkov. In this paper, we investigate the interaction of an ultrarelativistic electron beam head-on colliding with an ultraintense laser pulse and focus on the effects of photon polarization in NBW pair production process. To provide an accurate analysis of the produced pair polarization, we employ fully polarization resolved NBW probabilities, i.e., resolved as in incoming photon polarization as well as in the created electron and positron polarizations.…”

Generation of quasi-monoenergetic positron beams in chirped laser fields

“…The phenomenology of the process has been investigated theoretically in various types of laser field. First in monochromatic [3], and constant crossed fields [3,27] and more recently in finite laser pulses [28][29][30], as well as two-colour [31] and double-pulse fields [32][33][34]. As in NLC process, harmonic structure also arises in the outgoing electron-positron pair spectra operating in a manycycle laser pulse.…”