Cosmological CP odd axion field as the coherent Berry's phase of the Universe

Understand

We consider a dark matter (DM) model offering a very natural explanation of the observed relation, $\Omega_{\rm dark} \sim \Omega_{\rm visible}$.

• This generic consequence of the model is a result of the common origin of both types of matter (DM and visible) which are formed during the same QCD transition.
• The masses of both types of matter in this framework are proportional to one and the same dimensional parameter of the system, $\Lambda_{\rm QCD}$.
• The focus of the present work is the detail study of the dynamics of the $\cal{CP}$-odd coherent axion field $a(x)$ just before the QCD transition.