QED Fermions in a noisy magnetic field background

TL;DR

This paper investigates how spatially fluctuating magnetic fields affect fermion propagators in QED, revealing noise-dependent modifications to effective charge and refraction index relevant for high-energy physics scenarios.

Contribution

It introduces a novel analysis of magnetic noise effects on QED fermions using the replica formalism, extending understanding of inhomogeneous magnetic backgrounds.

Findings

Magnetic noise alters fermion quasi-particle parameters.

Effective charge and refraction index depend on noise magnitude.

Results applicable to heavy-ion collisions and early universe conditions.

Abstract

We consider the effects of a noisy magnetic field background over the fermion propagator in QED, as an approximation to the spatial inhomogeneities that would naturally arise in certain physical scenarios, such as heavy-ion collisions or the quark-gluon plasma in the early stages of the evolution of the Universe. We considered a classical, finite and uniform average magnetic field background $\langle\mathbf{B}(\mathbf{x})\rangle = \mathbf{B}$, subject to white-noise spatial fluctuations with auto-correlation of magnitude $\Delta_B$. By means of the Schwinger representation of the propagator in the average magnetic field as a reference system, we used the replica formalism to study the effects of the magnetic noise in the form of renormalized quasi-particle parameters, leading to an effective charge and an effective refraction index, that depend not only on the energy scale, as usual, but also on the magnitude of the noise $\Delta_B$ and the average field $\mathbf{B}$.