Dirac neutrinos from Peccei-Quinn symmetry: two examples

We aim to explain the nature of neutrinos using Peccei-Quinn symmetry. We discuss two simple scenarios, one based on a type-II Dirac seesaw and the other in a one-loop neutrino mass generation, which solve the strong CP problem and naturally lead to Dirac neutrinos. In the first setup latest neutrino mass limit gives rise to axion which is in the reach of conventional searches. Moreover, we have both axion as well as WIMP dark mater for our second set up.
Comment: 11 pages, 4 figures ; v2: Version to appear in Nuclear Physics B, Section 2.2 has been expanded