Quarks in an External Electric Field in Finite Temperature Large N Gauge Theory
Tameem Albash, Veselin Filev, Clifford V. Johnson, Arnab Kundu
TL;DR
The paper investigates how a background electric field affects a large-N SU(N) gauge theory with fundamental quarks using holographic D7-brane probes in an AdS$_5$-Schwarzschild$ imes$S$^5$ background. By turning on a worldvolume electric field and performing a Legendre transform to treat the induced current, the authors map out the D7-brane embeddings and extract the quark mass, condensate, and current, uncovering a zero-temperature first-order meson-dissociation transition that acts as an insulator-to-metal transition. At finite temperature, this dissociation persists and couples to the usual meson-melting transition, yielding a phase diagram where increasing the electric field lowers the meson binding energy and hence reduces the melting temperature. The study also analyzes meson spectroscopy via quadratic fluctuations, showing dissipation and quasinormal-mode behavior in the melted (black-hole) phase, with conical singularities in some high-field solutions pointing to the need for stringy corrections. Overall, the work highlights rich nonperturbative dynamics due to external fields in holographic gauge theories and connects to analogous phenomena in condensed matter contexts.
Abstract
We use a ten dimensional dual string background to aspects of the physics large N four dimensional SU(N) gauge theory, where its fundamental quarks are charged under a background electric field. The theory is N=2 supersymmetric for vanishing temperature and electric field. At zero temperature, we observe that the electric field induces a phase transition associated with the dissociation of the mesons into their constituent quarks. This is an analogue of an insulator-metal transition, since the system goes from being an insulator with zero current (in the applied field) to a conductor with free charge carriers (the quarks). At finite temperature this phenomenon persists, with the dissociation transition become subsumed into the more familiar meson melting transition. Here, the dissociation phenomenon reduces the critical melting temperature.