Spectral representation of the particle production out of equilibrium - Schwinger mechanism in pulsed electric fields

Abstract

We develop a formalism to describe the particle production out of equilibrium in terms of dynamical spectral functions, i.e. Wigner transformed Pauli-Jordan's and Hadamard's functions. We take an explicit example of a spatially homogeneous scalar theory under pulsed electric fields and investigate the time evolution of the spectral functions. In the out-state we find an oscillatory peak in Hadamard's function as a result of the mixing between positive- and negative-energy waves. The strength of this peak is of the linear order of the Bogoliubov mixing coefficient, whereas the peak corresponding to the Schwinger mechanism is of the quadratic order. Between the in- and the out-states we observe a continuous flow of the spectral peaks together with two transient oscillatory peaks. We also discuss the medium effect at finite temperature and density. We emphasise that the entire structure of the spectral functions conveys rich information on real-time dynamics including the particle production.

15 pages, 5 figures

References in corpus (5)

• Dynamically assisted Schwinger mechanism
• Schwinger pair production in space- and time-dependent electric fields: Relating the Wigner formalism to quantum kinetic theory
• Effective Action of QED in Electric Field Backgrounds
• Particle production in field theories coupled to strong external sources. II: Generating functions
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• Evolution to the Quark-Gluon Plasma
• Particle Interferometry in a Moat Regime
• Thermally versus dynamically assisted Schwinger pair production
• Schwinger Mechanism with Stochastic Quantization
• Unruh effect and condensate in and out of an accelerated vacuum