Title: Photon-ALP interaction as a measure of initial photon polarization
Abstract: Axionlike particles (ALPs) are very light, neutral, spin zero bosons predicted by superstring theory. ALPs interact primarily with two photons, and in the presence of an external magnetic field, they generate photon-ALP oscillations and the change of the polarization state of photons. While well motivated from a theoretical point of view, hints on ALP existence come from astrophysics. In this paper, we state and demonstrate some theorems about a strict relationship between initial photon polarization and photon-ALP conversion probability, which can be extrapolated by observed astrophysical spectra, so that in the presence of ALPs flux-measuring observatories become also polarimeters.