Radiation Gauge in AdS/QCD: inadmissibility and implications on spectral functions in the deconfined phase

TL;DR

This paper examines the issues with the radiation gauge choice in AdS/QCD models for black hole backgrounds, revealing its impact on spectral functions and anisotropy, especially under magnetic fields.

Contribution

It identifies a subtlety in gauge fixing in AdS/QCD and demonstrates its significant effects on spectral functions and anisotropy in the deconfined phase.

Findings

Spectral functions spread with momentum

Breaking of isotropy in spectral functions

Magnetic field dependence of spectral features

Abstract

We point out a subtlety in choosing the radiation gauge (A_z=0 combined with the Lorenz gauge) for gauge fields in AdS/QCD for black hole backgrounds. We then demonstrate the effect of this on the momentum-dependence of the spectral functions of the J/psi vector meson, showing a spreading with momentum and a breaking of isotropy, in contrast to previous results in the literature. We also discuss the dependence on a background magnetic field, following our earlier proposed model.