Wednesday 11 October 2017 

Speaker: Professor Pierre Sikivie (University of Florida)


Title: "The Search for Axions”

Abstract: The axion is a hypothetical particle proposed, approximately 40 years ago, to explain why the strong interactions 
are P and CP invariant. Additional motivation for its existence is due to the fact that a cold population of axions is 
naturally produced in the early universe. These cold axions may constitute the dark matter today. I'll briefly review the 
limits on the axion from particle physics, stellar evolution and cosmology. The various constraints suggest that the axion 
mass is in the micro-eV to milli-eV range. In this range, its interactions are so weak that the axion was once thought 
invisible. Nonetheless a number of methods have been proposed to search for so-called "invisible" axions. I'll describe 
these techniques, the experiments that have implemented them, and the results that have been obtained so far.