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TUE: Tuesday Contributed Sessions

TUE 9: Quantum Physics in Strong Fields: Contributed Session to Symposium

TUE 9.6: Talk

Tuesday, September 9, 2025, 15:30–15:45, ZHG101

Scattering matrix approach to dynamical Sauter-Schwinger process: vortex- vs. spiral structures — •Mateusz Majczak, Katarzyna Krajewska, Jerzy Kamiński, and Adam Bechler — Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland

The dynamical Sauter-Schwinger mechanism of electron-positron (e⁻e⁺) pair creation by electric field pulses is considered using the S-matrix approach and reduction formulas. They lead to the development of framework that treats the external electric field to all orders and is based on the solutions of the Dirac equation with the so-called Feynman- or anti-Feynman boundary conditions. The asymptotic properties of those solutions are linked to the electron and positron spin(helicity)-resolved probability amplitudes. Most importantly, the corresponding spin- or helicity-resolved distributions, when summed over spin or helicity configurations, reproduce the momentum distributions of created particles calculated with other methods that are typically used in this context, such as the DHW function approach. In contrast to those approaches, however, the S-matrix method provides the information about the phase of the probability amplitude of e⁻e⁺ pair creation. Therefore, it allows one to study the vortex- and spiral structures in momentum distributions of produced particles. As it follows from our numerical studies, a momentum spiral is created as a result of the vortex-antivortex annihilation. Moreover, as we show, in order to observe such annihilation one has to drive the pair creation with electric field pulses of the time reversal symmetry.

Keywords: Sauter-Schwinger process; Pair creation; Scattering matrix; Vortex structure; Momentum spiral