Trident Pair Production Research Articles

Rise and fall of laser-intensity effects in spectrally resolved Compton process

The laser intensity dependence of nonlinear Compton scattering is discussed in some detail. For sufficiently hard photons with energy ω′, the spectrally resolved differential cross section dσ/dω′| ω′=const, rises from small toward larger laser intensity parameter ξ, reaches a maximum, and falls toward the asymptotic strong-field region. Such a rise and fall of a differential observable is to be contrasted with the monotonously increasing laser intensity dependence of the total probability, which is governed by the soft spectral part. We combine that hard-photon yield from Compton scattering with the seeded Breit–Wheeler pair production in a folding model and obtain a rapidly increasing e + e − pair number at ξ ≲ 4. Laser bandwidth effects are quantified in the weak-field limit of the related trident pair production.

Laser pulse-length effects in trident pair production

Laser pulses facilitate multiphoton contributions to the trident pair production , where the label L indicates a laser field dressed electron (e−) or positron (e+ ). We isolate the impact of the pulse envelope in the trident S matrix element, formulated within the Furry picture, in leading order of a series expansion in the classical nonlinearity parameter a0. Generally, the Fourier transform of the envelope carries the information on the pulse length, which becomes an easily tractable function in the case of a pulse envelope. The transition to a monochromatic laser wave can be handled in a transparent manner, as also the onset of bandwidth effects for short pulses can be factorized out and studied separately.

Nonlinear trident pair production in an arbitrary plane wave: A focus on the properties of the transition amplitude

The process of nonlinear electron-positron pair production by an electron colliding with an arbitrary plane wave electromagnetic field (nonlinear trident pair production) is studied analytically and numerically. Special emphasis is put on the properties of the transition amplitude. In fact, its original expression as resulting from applying the Wick's theorem turns out to be divergent and not to manifestly fulfill gauge invariance. By restoring the latter, the amplitude is regularized and investigated in different regimes. In particular, the amplitude is divided into a two-step and a one-step contributions, depending on the scaling dependence on the laser pulse duration. The corresponding contributions to the positron angular distribution spectra and the resulting interference terms are studied numerically emphasizing the possibility of measuring experimentally the contribution of the one-step contribution.

Trident pair production in plane waves: Coherence, exchange, and spacetime inhomogeneity

We study the trident process in inhomogeneous plane wave background fields. We obtain compact analytical expressions for all terms in the probability, including the exchange part, for an arbitrarily shaped plane wave. We evaluate the probability numerically using complex deformation of lightfront time integrals and derive various analytical approximations. Our results provide insights into the importance of the one-step and exchange parts of the probability relative to the two-step process, and into the convergence to the locally constant field approximation.

Circular dichroism in nonlinear electron-positron pair creation

The trident pair production by X-ray photons in the presence of a powerful laser field is considered in the framework of strong-field quantum electrodynamics. The dependence of differential probability rates of the process on the handedness of circular polarizations of X-ray and laser photons is illustrated. It is revealed that circular dichroism effects are most pronounced for short pulse durations of the driving fields.

Trident pair production in colliding bright x-ray laser beams

The magnificent development of strong X-ray lasers motivates the advancement of pair production process studies into higher laser frequency region. In this paper, a resonant electron-positron pair production process with the absorption of two X-ray photons is considered in the impact of an energetic electron at the overlap region of two colliding X-ray laser beams. Laser-dressed QED method is justified to tackle the complexity of the corresponding multiple Feynman diagrams calculation. The dependence of the production rate as well as the positron energy distribution on the relative angles among the directions of the two laser wave vectors and the incoming electron momentum is revealed. It is shown that the non-plane wave laser field configuration arouses novel features in the pair production process compared to the plane-wave case.

Trident pair production in a constant crossed field

We isolate the two-step mechanism involving a real intermediate photon from the one-step mechanism involving a virtual photon for the trident process in a constant crossed field. The two-step process is shown to agree with an integration over polarised sub-processes. At low to moderate quantum non-linearity parameter, the one-step process is found to be suppressed. When the parameter is large, the two decay channels are comparable if the field dimensions are not much greater than the formation length.

Trident Pair Production in Strong Laser Pulses

We calculate the trident pair production amplitude in a strong laser background. We allow for finite pulse durations, while still treating the laser fields nonperturbatively in strong-field QED. Our approach reveals explicitly the individual contributions of the one-step and two-step processes. We also expose the role gauge invariance plays in the amplitudes and discuss the relation between our results and the optical theorem.

ELECTRON IMPACT PROCESSES IN SUPER-INTENSE LASER FIELDS

We discuss the motion of an electron in a classical electromagnetic wave, including ponderomotive force effects. To describe electron impact stimulated reactions under the action of superstrong laser field we formulate instant-impact approximation. We demonstrate how it can be applied to calculate hard electron-nuclear processes for obtaining the reaction rates for such effects as trident pair production, hard X-ray generation, electrostimulated nuclear fission, and both ions and nuclei excitation by electron impact in the laser field.

Geometric limitations of the efficient generation of antihydrogen in an intense laser focus

The need to produce antihydrogen as fuel for interstellar missions has been discussed by Forward and other. The use of lasers (10 6 J, 300 fs pulses) may result in 10 6 times higher conversion efficiencies than the use of accelerators for antiproton production. One problem is the radial ejection of the relativistically oscillating particles from the laser focus. A numerical calculation of the quiver drift has been performed and it was found that for the focus geometries of present day technologies, the interaction time is not too long for acheiving the necessary trident pair production in the laser focus.