Speaker: Kristjan Müürsepp (NICPB, Tallinn, Estonia)

A pseudo Nambu-Goldstone boson (PNGB) coupled to a confining gauge group via an anomalous  term is characterised, during the confining phase transition, by a temperature dependent mass.

I will study the possibility that a PNGB  coupled to a hidden gauge group  undergoing confinement  at a temperature different from the QCD  confining temperature could hit a level crossing with the QCD axion. This can  trigger axion-dark axion conversion. After describing the dynamics of the two axion system, I will address possible applications in cosmology.