Response of a Holographic Confining Theory to External Electromagnetic Fields

Indirect approaches can sometimes lead to solutions to problems that are difficult or impossible to solve by direct methods. Notions of duality, in which a mapping is identified between two seemingly different theories, are especially fruitful sources of indirect methods. In particular, gauge/gravity duality, in which quantum field theories are seen as equivalent to theories of gravity in one higher dimension, has led to solutions to previously intractable problems. We utilize a form of gauge/gravity duality (the so-called "AdS/QCD correspondence") to investigate the response of a QCD-like gauge theory —i.e., holographically dual to the Andreev-Zakharov model (a deformed AdS₅ model)— to constant electromagnetic fields. This approach enables us to discuss the Schwinger effect for quark-antiquark pairs. We study the Schwinger effect for three cases: a quadratic correction, a logarithmic correction, and both quadratic and logarithmic corrections. For each case, we set values of parameters such that the quark-antiquark potential in the holographic QCD model matches experimental data and lattice results. We show that an external magnetic field perpendicular to the electric field decreases the quark-antiquark pair production rate. On the contrary, a pure parallel magnetic field increases the pair production rate if a perpendicular magnetic field is also present.