Holographic Photon Production with Magnetic Field in Anisotropic Plasmas

TL;DR

This paper studies how magnetic fields and pressure anisotropy affect thermal photon production in strongly coupled plasmas using gauge/gravity duality, revealing directional dependencies, resonances, and competing effects on meson melting.

Contribution

It introduces a model combining anisotropic geometry and magnetic fields to analyze photon spectra and resonance phenomena in strongly coupled plasmas.

Findings

Photon spectra are enhanced at large frequency along certain directions.

Resonance appears at moderate frequency for heavy quarks perpendicular to magnetic field.

Pressure anisotropy suppresses the resonance effect.

Abstract

We investigate the thermal photon production from constant magnetic field in a strongly coupled and anisotropic plasma via the gauge/gravity duality. The dual geometry with pressure anisotropy is generated from the axion-dilaton gravity action introduced by Mateos and Trancancelli and the magnetic field is coupled to fundamental matters(quarks) through the D3/D7 embeddings. We find that the photon spectra with different quark mass are enhanced at large frequency when the photons are emitted parallel to the anisotropic direction with larger pressure or perpendicular to the magnetic field. However, in the opposite conditions for the emitted directions, the spectra approximately saturate isotropic results in the absence of magnetic field. On the other hand, a resonance emerges at moderate frequency for the photon spectrum with heavy quarks when the photons move perpendicular to the magnetic field. The resonance is more robust when the photons are polarized along the magnetic field. On the contrary, in the presence of pressure anisotropy, the resonance will be suppressed. There exist competing effects of magnetic field and pressure anisotropy on meson melting in the strongly coupled super Yang-Mills plasma, while we argue that the suppression led by anisotropy may not be applied to the quark gluon plasma.