Magnetized Einstein\u2013Maxwell-dilaton model under an external electric field

Abstract

We employ an analytic solution of a magnetized Einstein–Maxwell-dilaton gravity model whose parameters have been determined so that its holographic dual has the most similarity to the confining QCD-like theories. Analyzing the total potential of a quark–antiquark pair, we are able to investigate the effect of an electric field on different phases of the background which are the thermal AdS and black hole phases. This is helpful for better understanding of the confining character and the phases of the system. We find out that the field theory dual to the black hole solution is always deconfined, as expected. However, although the thermal AdS phase generally describes the confining phase, for quark pairs parallel to B (longitudinal case) with B>B_{mathrm {critical}} the response of the system mimics the deconfinement, since there is no IR wall in the bulk and the critical field E_s=0, as is the case for the deconfined phase. We moreover observe that in the black hole phase with sufficiently small values of mu and in the thermal AdS phase, for both longitudinal and transverse cases, the magnetic field enhances the Schwinger effect, which can be termed as the inverse magnetic catalysis (IMC). This is deduced both from the decrease of critical electric fields and decreasing the height and width of the total potential barrier the quarks are facing with. However, by increasing mu to higher values, IMC turns into magnetic catalysis, as also observed from the diagram of the Hawking–Page phase transition temperature versus B for the background geometry.