Hyperfine splitting and the Zeeman effect in holographic heavy-light mesons

Abstract

We inspect the mass spectrum of heavy-light mesons in deformed $\mathcal{N}=2$ super Yang-Mills theory using the AdS/CFT correspondence. We demonstrate how some of the degeneracies of the supersymmetric meson spectrum can be removed upon breaking the supersymmetry, thus leading to the emergence of a hyperfine structure. The explicit SUSY breaking scenarios we consider involve on the one hand, tilting one of the two fundamental D7-branes inside the internal ${\mathbb{R}}^{6}$ space, and on the other hand, applying an external magnetic field on the (untilted) branes. The latter scenario leads to the well-known Zeeman effect, which we inspect for both weak and strong magnetic fields.