High Energy Physics Seminars

The best explanation for the lack of CP violation by strong interactions involves the existence of axions: light, weakly interacting spin-0 particles. The PVLAS experiment, hep-ex/0507107, reports seeing a rotation of the polarization of 0.1 W laser light in a transverse magnetic field consistent with having an axion but with an extremely large (unlikely?) ratio of electromagnetic to color anomalies. JLab's FEL Axion group plans to use its 10 kW free-electron laser to provide a rigorous check on the PVLAS result and to look for photon regeneration due to propagating axions. I will review the reasons for having axions and explain why experiments of this type are so important.