Quantum Criticality via Magnetic Branes

Understand

Holographic methods are used to investigate the low temperature limit, including quantum critical behavior, of strongly coupled 4-dimensional gauge theories in the presence of an external magnetic field, and finite charge density.

• In addition to the metric, the dual gravity theory contains a Maxwell field with Chern-Simons coupling.
• In the absence of charge, the magnetic field induces an RG flow to an infrared AdS$_3 \times {\bf R}^2$ geometry, which is dual to a 2-dimensional CFT representing strongly interacting fermions in the lowest Landau level.
• Two asymptotic Virasoro algebras and one chiral Kac-Moody algebra arise as {\sl emergent symmetries} in the IR.