Particle creation and the Schwinger model

TL;DR

This paper investigates particle creation in the Schwinger model with an external source, demonstrating the equivalence of full quantum and semiclassical approaches, and suggesting future studies on the massive model as a testbed for quantum gravity analogies.

Contribution

It shows the semiclassical approach's validity in the massless Schwinger model by matching results with the fully quantized solution, and proposes extending this analysis to the massive case.

Findings

Exact agreement between quantum and semiclassical calculations

Validation of semiclassical approximation for the massless Schwinger model

Potential use of the massive model as a quantum gravity analog

Abstract

We study the particle creation process in the Schwinger model coupled with an external classical source. One can approach the problem by taking advantage that the full quantized model is solvable and equivalent to a (massive) gauge field with a non-local effective action. Alternatively, one can also face the problem following the standard semiclassical route. This means quantizing the massless Dirac field and considering the electromagnetic field as a classical background. We evaluate the energy created by a generic, homogeneous, and time-dependent source. The results exactly match in both approaches. This proves in a very direct and economical way the validity of the semiclassical approach for the (massless) Schwinger model, in agreement with previous analysis based on the linear response equation. Our discussion suggests that a similar analysis for the massive Schwinger model could be used as a non-trivial laboratory to confront a fully quantized solvable model with its semiclassical approximation, therefore mimicking the long-standing confrontation of quantum gravity with quantum field theory in curved spacetime.