Birefringence and non-transversality of light propagation in an ultra-strongly magnetized vacuum

TL;DR

This paper investigates how an ultra-strong magnetic field affects light propagation in vacuum, revealing non-transversality and birefringence effects with potential astrophysical implications.

Contribution

It introduces the concept of non-transversality in vacuum birefringence under strong magnetic fields and provides analytic results for ultra-strong regimes.

Findings

Parallel mode is no longer transverse in a magnetized vacuum.

Analytic expressions derived for ultra-strong magnetic fields.

Potential implications for astrophysical observations.

Abstract

The birefringence phenomenon in the vacuum with a constant magnetic background of arbitrary strength is considered within the framework of the effective action approach. A new feature of the birefringence in a magnetized vacuum is that the parallel mode, which is polarized parallel to the plane containing the magnetic field and the photon wave vector, is no longer transverse. We have studied this feature in detail for arbitrary magnetic field and provided analytic results for the ultra-strong magnetic field regime. Possible physical implications of our results in astrophysics are discussed.