Work

Helicity effects in the dynamically assisted Schwinger mechanism

Year: 2026

Type: article

Abstract: We study vacuum electron-positron pair production in a spatially uniform bichromatic electric field within the quantum-kinetic framework for fermions. The external background models the superposition of two counterpropagating circularly polarized laser pulses and combines a strong slowly varying component with a weak rapidly oscillating one. We analyze the weak-field multiphoton regime, the strong-field tunneling regime, and their combination corresponding to the dynamically assisted Schwinger effect. Our main focus is on helicity-resolved observables. The main result is that, within the parameter range considered here, the ratio of the momentum distributions for opposite helicities is governed predominantly by the polar angle with respect to the propagation axis and depends only weakly on the momentum magnitude and azimuthal angle. Dynamical assistance enhances not only the total yield but also the helicity asymmetry: right- and left-handed electrons preferentially populate opposite momentum half-spaces. The corresponding asymmetry becomes more pronounced as the weak-field frequency is increased. These results identify a distinct helicity feature of the dynamically assisted Schwinger effect in rotating strong-field backgrounds and provide a compact characterization of the associated helicity-resolved spectra.

Source: Nuclear Physics B

DOI: 10.1016/j.nuclphysb.2026.117693

Authors: A.I. Baksheev, V.A. Bokhan, A. Kudlis, I.A. Aleksandrov

Institutions: St Petersburg University, University of Iceland

Language: English

Topic: Quantum Electrodynamics and Casimir Effect

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funders: Icelandic Centre for Research, Russian Science Foundation

Award: G4696175901