Effect of interference on the trident process in a constant crossed field

Abstract

We perform a complete calculation of electron-seeded pair creation (the trident process) in a constant crossed electromagnetic background. Unlike earlier treatments, we include the interference between exchange diagrams. We find that this exchange interference can be written as a contribution solely to the one-step process, and for small quantum nonlinearity parameter is of the same order as other one-step terms. We find that the exchange interference further suppresses the one-step process in this parameter regime. Our findings further support the crucial assumption made in laser-plasma simulation codes that at high intensities, the trident process can be well approximated by the repeated iteration of the single-vertex subprocesses. The applicability of this assumption to higher-vertex processes has fundamental importance to the development of simulation capabilities. DOI: 10.1103/PhysRevD.98.016005 When an electron propagates in an intense electromagnetic (EM) field, there is a finite probability that the radiation it produces will decay into an electron-positron pair. If the EM field is weak, in that the effect is perturbative in the charge-field interaction, it corresponds to the linear Breit-Wheeler process [1], where one photon from the background collides with the photon radiated by the electron to produce a pair. Although important in astrophysical contexts [2,3], this linear process has still to be measured in a terrestrial experiment [4]. If the laser pulse intensity is strong, in that all orders of the charge-field interaction must be included in calculations, the photon decay into a pair corresponds to the nonlinear BreitWheeler process. A quarter of a century after electronseeded pair creation was first calculated theoretically in constant magnetic [5] and crossed [6] backgrounds, the combination of nonlinear Compton scattering followed by the nonlinear Breit-Wheeler process was measured in the landmark E144 experiment performed at the Stanford Linear Accelerator Center (SLAC) [7,8]. The importance of this experiment to the laser strong-field QED community can be understood in light of continued interpretation and analysis of the E144 results in the literature [9][10][11].In addition to also having astrophysical importance, a measurement of electron-seeded pair creation in a terrestrial laser-particle collision would allow the study of nonperturbative quantum field theory. As the intensity of the laser pulse increases, for a fixed frequency and seed particle energy, the process moves from the perturbative, to the multiphoton and finally to a tunneling regime [9], in which dependency on the charge-field coupling takes a nonperturbative form.To aid experimental design and analysis, there is an interest in including electron-seeded pair creation in traditional plasma particle-in-cell (PIC) code, using Monte Carlo techniques. Lowest-order processes such as nonlinear Compton scattering [12,13] and photon-seeded pair creation [14][15][16] are included in various simulation codes [17][18][19] and their ...

Single and double nonlinear Compton scattering

“…In [1] we studied the trident process [2][3][4][5][6][7][8], e − → 2e − + e + , in plane-wave background fields, and derived compact expressions for the probability for arbitrary background field shapes. Here we will apply the same methods to another second-order process, namely double nonlinear Compton scattering [9][10][11][12][13][14], where the incoming electron emits two photons, e − → e − + 2γ.…”

Thermally versus dynamically assisted Schwinger pair production

“…However, the trident process can scale quadratically rather than linearly in the volume (see e.g. [4,5,[9][10][11] for the zero-temperature constant-crossed plane wave case), so it would be interesting to study how large the trident contribution is compared to the O(α 2 ) process considered here. ACKNOWLEDGMENTS G. T. thanks Holger Gies for inspiring and useful discussions and for reading and commenting on the manuscript, and Oliver Gould for interesting discussions.…”

“…Pure Schwinger pair production [1][2][3] by a constant electric field alone is unlikely to be observed any time soon, but there are non-spontaneous processes which have similar nonperturbative features and could occur at much lower intensities. One example is trident pair production e − → 2e − + e + [4][5][6][7][8][9][10][11][12]. This requires much lower intensities because in the rest frame of a highenergy electron the field strength is much higher, and in the semiclassical regime this process has a similar nonperturbative exponential behavior as the Schwinger mechanism [4][5][6]10].…”

Trident process in laser pulses

“…The trident process, e − → 2e − + e + , in laser fields has recently attracted renewed interest [1][2][3][4][5][6] following [7][8][9] and the classic experiment at SLAC [10]. While this process was studied already in the early seventies [11,12], it is only with modern high-intensity lasers that it is becoming experimentally important.…”