Konwersatorium im. Leopolda Infelda

I will discuss theoretical motivations for the existence of axions and bounds on their masses and interactions coming from astrophysics andcosmology. I will describe arguments to propose axions as natural ColdDark Matter candidates. I will present existing experiments searching foraxions and in particular experiment OSQAR at CERN. On the theory sideslightly enlarged Standard Model with conformal symmetry naturallyincludes axions as (pseudo)Goldstone bosons of spontaneously broken lepton number symmetry with very small couplings correlated with small neutrino masses.