Composite neutrinos and the QCD axion: Baryogenesis, dark matter, small Dirac neutrino masses, and vanishing neutron electric dipole moment

We consider a chiral gauge theory from which light composite Dirac neutrinos dynamically emerge, augmented by a QCD axion to solve the strong CP problem. We show that an interplay between the composite sector and the axion can also simultaneously lead to successful baryogenesis and generate a correct dark matter abundance via cogenesis without contradicting present constraints. We predict Delta N-eff >= 0.14 and m(a) in the range O(10) mu eV-O(10) meV, which can be firmly tested by upcoming CMB experiments and axion searches.

Automated summary

The proposed model combines a chiral gauge theory with a QCD axion to address the emergence of Dirac neutrinos and solve the strong CP problem. The interplay between the composite sector and the axion can also explain baryogenesis and dark matter abundance through cogenesis without violating current constraints. Predictions include a Delta N-eff >= 0.14 and m(a) in the range O(10) mu eV-O(10) meV, which can be tested by upcoming CMB experiments and axion searches.