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

Abstract

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 $\mathrm{\ensuremath{\Delta}}{N}_{\mathrm{eff}}\ensuremath{\ge}0.14$ and ${m}_{a}$ in the range $O(10)\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}--O(10)\text{ }\text{ }\mathrm{meV}$, which can be firmly tested by upcoming CMB experiments and axion searches.

Topics & Concepts