Axion-like particle oscillations

TL;DR

This paper explores how mixing between multiple axion-like particles (ALPs), similar to neutrino oscillations, can affect astrophysical signals and potentially reduce the expected signals in experiments like CAST.

Contribution

It introduces the concept of ALP mixing analogous to neutrino oscillations and analyzes its impact on astrophysical ALP detection signals.

Findings

Mixing between ALPs can significantly alter expected signals.

The phenomenon may reduce the effectiveness of current ALP detection experiments.

Theoretical framework for ALP mixing analogous to neutrino oscillations.

Abstract

String theory compactifications may generate many light axion-like particles (ALPs) with weak couplings to electromagnetism. In general, a large number of ALPs may exist, with a linear combination having a potentially observable coupling to electromagnetism. The basis in which only one ALP couples to electromagnetism is in general misaligned with the mass basis. This leads to mixing between the `electromagnetic' ALP and a number of `hidden' ALPs that do not interact directly with the photon. The process is analagous to neutrino oscillations. I will discuss the phenomenological consequences of this mixing for astrophysical ALP signals, in particular showing that it may significantly reduce the predicted signal in experiments such as the CERN Axion Solar Telescope.