Worldline sphaleron for thermal Schwinger pair production

TL;DR

This paper investigates how increasing temperature shifts Schwinger pair production from quantum tunnelling to a classical thermal process, calculating the rate for both spinor and scalar QED including semiclassical effects.

Contribution

It introduces the concept of a worldline sphaleron for thermal Schwinger pair production and provides a comprehensive rate calculation applicable to various particles and conditions.

Findings

Thermal Schwinger pair production rate exceeds perturbative photon fusion.

Derived rate is faster than zero-temperature Schwinger process.

Results are applicable to magnetic monopole production in heavy ion collisions.

Abstract

With increasing temperatures, Schwinger pair production changes from a quantum tunnelling to a classical, thermal process, determined by a worldline sphaleron. We show this and calculate the corresponding rate of pair production for both spinor and scalar quantum electrodynamics, including the semiclassical prefactor. For electron-positron pair production from a thermal bath of photons and in the presence of an electric field, the rate we derive is faster than both perturbative photon fusion and the zero temperature Schwinger process. We work to all-orders in the coupling and hence our results are also relevant to the pair production of (strongly coupled) magnetic monopoles in heavy ion collisions.