Photon-ALP oscillations inducing modifications to photon polarization

Understand

Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to complete the standard model of elementary particles.

• ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field.
• They are attracting increasing interest since photon-ALP oscillations produce deep consequences in very-high-energy (VHE) astrophysics.
• Two hints for the existence of an ALP have recently been proposed.