Holographic entanglement entropy in the QCD phase diagram under external magnetic field

TL;DR

This paper investigates how holographic entanglement entropy behaves in the QCD phase diagram under external magnetic fields, revealing phase transition indicators and orientation-dependent effects.

Contribution

It introduces a detailed holographic analysis of entanglement entropy in QCD phases with magnetic fields, highlighting orientation effects and phase transition signals.

Findings

Swallow-tail structure indicates phase transition in perpendicular magnetic field.

Monotonic behavior in parallel orientation shows no transition.

Magnetic field influences the multivaluedness of entanglement entropy at high chemical potential.

Abstract

In this work, we explore holographic entanglement entropy in the QCD phase diagram under an external magnetic field using an Einstein-Maxwell-dilaton model. We consider both the specious-confinement and deconfined phases. In the perpendicular magnetic field orientation, the strip length shows three distinct branches, and the entanglement entropy develops a swallow-tail structure, indicating a transition between connected and disconnected entanglement surfaces. For the parallel orientation, the behavior is monotonic and no transition occurs. In addition, the difference in entanglement entropy changes smoothly with temperature at small chemical potential, but becomes multivalued at large chemical potential. Increasing the magnetic field restores single-valued behavior. These results are consistent with the black hole thermodynamics and the QCD phase diagram. Our findings show that entanglement entropy can serve as an effective probe of the QCD phase transition.