Abstract: | The recent results by the PVLAS group on possible changes of polarization of laser light in a transverse magnetic field are beyond the QED expectations by many orders of magnitude.If confirmed,they may indicate new physics associated with ultra-light particles.I describe here how the polarization of light is modified in an external magnetic field by interactions with a spin-zero particle of no definite parity.While the PVLAS-type experiments cannot tell such a particle from one with definite parity,the pari... |