Vacuum polarization and pair production in time-dependent electric fields: A quantum-kinetic-equation approach

The evolution of the vacuum state in a time-dependent external electric field of arbitrary polarization is investigated within a nonperturbative framework of quantum kinetic equations (QKEs). In our previous work [Phys. Rev. Res. 6, 043009 (2024)], a revised version of the QKEs was derived by using an adiabatic basis constructed from one-particle Hamiltonian eigenfunctions in a spatially homogeneous electric field. In this study, we present an extensive analysis of these equations with particular emphasis on observable quantities. Specifically, we compute momentum-resolved particle yields, the induced electron-positron current, the energy-momentum tensor, and the angular-momentum tensor. We also discuss in detail the charge-renormalization procedure required to remove logarithmic divergences. It is shown that our results are consistent with the previous findings obtained via the Dirac-Heisenberg-Wigner formalism. Our analysis provides a firmer theoretical basis for investigations of nonperturbative effects in strong electric fields.

💡 Research Summary

The paper presents a comprehensive, non‑perturbative treatment of vacuum decay and electron‑positron pair creation in a spatially homogeneous, time‑dependent electric field of arbitrary polarization. Building on the authors’ earlier work (Phys. Rev. Res. 6, 043009 (2024)), the study derives a revised set of quantum kinetic equations (QKEs) by expanding the Heisenberg field operator in an adiabatic basis formed from the instantaneous eigenfunctions of the one‑particle Hamiltonian H_e(t)=α·