Parametric co-linear axion photon instability

TL;DR

This paper investigates a parametric instability in axion-electrodynamics where a strong laser pump decays into a scattered photon and an axion, leading to potential experimental detection of axions through polarization changes.

Contribution

It introduces a new parametric instability mechanism in axion-photon interactions and discusses its implications for axion detection using laser systems.

Findings

Exponential growth of axion modes due to the instability.

Laser polarization changes as a detectable signal.

Current laser systems can set bounds on axion parameters.

Abstract

Axions and axion-like particles generically couple to QED via the axion-photon-photon interaction. This leads to a modification of Maxwell's equations known in the literature as axion-electrodynamics. The new form of Maxwell's equations gives rise to a new parametric instability in which a strong pump decays into a scattered light wave and an axion. This axion mode grows exponentially in time and leads to a change in the polarisation of the initial laser beam, therefore providing a signal for detection. Currently operating laser systems can put bounds on the axion parameter space, however longer pulselengths are necessary to reach the current best laboratory bounds of light-shining through wall experiments.