AdS/CFT with Flavour in Electric and Magnetic Kalb-Ramond Fields

TL;DR

This paper explores how pure-gauge Kalb-Ramond B fields influence gauge/gravity duals with flavour, revealing effects on meson stability, chiral symmetry breaking, and meson spectra under electric and magnetic fields.

Contribution

It introduces the effects of pure-gauge Kalb-Ramond B fields in gauge/gravity duals with flavour, analyzing their impact on mesons and chiral symmetry at finite temperature and zero temperature.

Findings

Magnetic B field stabilizes mesons and induces chiral symmetry breaking at finite temperature.

Electric B field causes a singular region requiring gauge field activation on the brane.

Weak electric B field causes a Stark-like mass shift in the meson spectrum.

Abstract

We investigate gauge/gravity duals with flavour for which pure-gauge Kalb-Ramond B fields are turned on in the background, into which a D7 brane probe is embedded. First we consider the case of a magnetic field in two of the spatial boundary directions. We show that at finite temperature, i.e. in the AdS-Schwarzschild background, the B field has a stabilizing effect on the mesons and chiral symmetry breaking occurs for a sufficiently large value of the B field. Then we turn to the electric case of a B field in the temporal direction and one spatial boundary direction. In this case, there is a singular region in which it is necessary to turn on a gauge field on the brane in order to ensure reality of the brane action. We find that the brane embeddings are attracted towards this region. Far away from this region, in the weak field case at zero temperature, we investigate the meson spectrum and find a mass shift similar to the Stark effect.