Holographic chiral currents in a magnetic field

Abstract

In the presence of a quark chemical potential, a magnetic field induces an axial current in the direction of the magnetic field. We compute this current in the Sakai-Sugimoto model, a holographic model which, in a certain limit, is dual to large-N_c QCD. We also compute the analogous vector current, for which an axial chemical potential is formally introduced. This vector current can potentially be observed via charge separation in heavy-ion collisions. After implementing the correct axial anomaly in the Sakai-Sugimoto model we find an axial current in accordance with previous studies and a vanishing vector current, in apparent contrast to previous weak-coupling calculations.

Comments: 8 pages, to appear in the proceedings of "New Frontiers in QCD 2010", Yukawa Institute for Theoretical Physics, Kyoto, Japan, Jan 18 - Mar 19, 2010