Electromagnetic instability and Schwinger effect in the Witten-Sakai-Sugimoto model with D0-D4 background

TL;DR

This paper uses the holographic Witten-Sakai-Sugimoto model with D0-D4 background to study electromagnetic instability and the Schwinger effect, revealing how the vacuum decay rate depends on the $ heta$ angle and temperature.

Contribution

It provides a holographic computation of the Schwinger effect in a D0-D4 background, linking vacuum decay to the $ heta$ angle and phase transitions in QCD-like theories.

Findings

Decay rate decreases with increasing $ heta$ angle.

Results match black D0-D4 configuration at zero temperature.

Hawking-Page transition interpreted as confinement/deconfinement transition.

Abstract

Using the Witten-Sakai-Sugimoto model in the D0-D4 background, we holographically compute the vacuum decay rate of the Schwinger effect in this model. Our calculation contains the influence of the D0-brane density which could be identified as the $\theta$ angle or chiral potential in QCD. Under the strong electromagnetic fields, the instability appears due to the creation of quark-antiquark pairs and the associated decay rate can be obtained by evaluating the imaginary part of the effective Euler-Heisenberg action which is identified as the action of the probe brane with a constant electromagnetic field. In the bubble D0-D4 configuration, we find the decay rate decreases when the $\theta$ angle increases since the vacuum becomes heavier in the present of the glue condensate in this system. And the decay rate matches to the result in the black D0-D4 configuration at zero temperature limit according to our calculations. In this sense, the Hawking-Page transition of this model could be consistently interpreted as the confined/deconfined phase transition. Additionally there is another instability from the D0-brane itself in this system and we suggest that this instability reflects to the vacuum decay triggered by the $\theta$ angle as it is known in the $\theta$-dependent QCD.