Abstract
We investigate the effect of a constant magnetic field background on the scalar QED pair production in a four-dimensional de Sitter spacetime ($\dsf$). We have obtained the pair production rate which agrees with the known Schwinger result in the limit of Minkowski spacetime and with the Hawking radiation in de Sitter spacetime (dS) in the zero electric field limit. Our results describe how the cosmic magnetic field affects the pair production rate in cosmological setups. In addition, using the zeta function regularization scheme we have calculated the induced current and examined the effect of a magnetic field on the vacuum expectation value of the current operator. We find that, in the case of a strong electromagnetic background the current responds as $E\cdot B$, while in the infrared regime, it responds as $B/E$, which leads to a phenomenon of infrared hyperconductivity. These results of the induced current have important applications for the cosmic magnetic field evolution.
Highlights
A fascinating effect in quantum field theory is the Schwinger effect [1]: the creation of pairs of particle and antiparticle out of the vacuum in the presence of a background electromagnetic field
We investigate the effect of a uniform magnetic field background on scalar QED pair production in a four-dimensional de Sitter spacetime
In the case of a strong electromagnetic background the current responds as E · B, while in the infrared regime, it responds as B=E, which leads to a phenomenon of infrared hyperconductivity
Summary
A fascinating effect in quantum field theory is the Schwinger effect [1]: the creation of pairs of particle and antiparticle out of the vacuum in the presence of a background electromagnetic field. The effect of a uniform magnetic field exhibits new properties of the Schwinger mechanism compared to a pure electric field in dS Another possible reason to consider an electromagnetic field in the early Universe would come from the observation of blazars leading to a lower bound for the magnetic field in the intergalactic medium: B > 6 × 10−18 G [29]. This paper aims at investigating the influence of the magnetic field on the Schwinger pair creation of charged scalars in dS4, by computing the semiclassical decay rate and analyzing the quantum vacuum expectation value of the current operator, which is equivalent to the exact one-loop approach including all one-loop diagrams.
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