Universal Holographic Chiral Dynamics in an External Magnetic Field

TL;DR

This paper investigates holographic gauge theories under external magnetic fields, revealing universal features of magnetic catalysis and deriving effective actions for pseudo Goldstone bosons with distinct dispersion relations.

Contribution

It extends holographic gauge theory analysis to various Dp/Dq systems, demonstrating universality in magnetic catalysis and deriving effective low-energy actions with novel dispersion relations.

Findings

D3/D7 system follows GMOR relation with relativistic dispersion

D3/D5 system exhibits quadratic dispersion and modified GMOR

Universality of magnetic catalysis across different Dp/Dq systems

Abstract

In this work we further extend the investigation of holographic gauge theories in external magnetic fields, continuing earlier work. We study the phenomenon of magnetic catalysis of mass generation in 1+3 and 1+2 dimensions, using D3/D7- and D3/D5-brane systems, respectively. We obtain the low energy effective actions of the corresponding pseudo Goldstone bosons and study their dispersion relations. The D3/D7 system exhibits the usual Gell-Mann--Oakes--Renner (GMOR) relation and a relativistic dispersion relation, while the D3/D5 system exhibits a quadratic non-relativistic dispersion relation and a modified linear GMOR relation. The low energy effective action of the D3/D5 system is related to that describing magnon excitations in a ferromagnet. We also study properties of general Dp/Dq systems in an external magnetic field and verify the universality of the magnetic catalysis of dynamical symmetry breaking.