Speaker
Description
The type-I Dirac seesaw extension is made to the DFSZ axion model, where light active neutrinos are Dirac particles and acquire mass through the canonical seesaw mechanism after the Peccei-Quinn and electroweak symmetry breaking, finding that neutrino mass can be approximated to $m_{\nu}≈vf_{a}/Λ_{UV}$, result which relates the three energy scales involved in the model: the mass of the heavy sterile Dirac fermions introduced ($Λ_{UV}$), Peccei-Quinn spontaneous symmetry breaking scale given by the axion coupling constant ($f_{a}$), and the electroweak scale ($v$). As a consequence, it was found that $10^{3}f_{a}∼Λ_{UV}$, hence neutrino Yukawa coupling associated to the QCD axion, which is candidate to dark matter, is highly suppressed (up to $10^{−10}$) in comparison to the Higgs. Dirac neutrino effective mass matrix is computed explicitly, whose components depend on active-sterile mixing parameters, the latter being new sources of CP violation. Therefore, the CP asymmetry factor and the baryon-antibaryon density are computed for the unflavoured leptogenesis, linking neutrino physics, QCD axion, and cosmological parameters into a same theoretical model.
