Leptogenesis driven by a Majoron

Abstract

We propose a leptogenesis scenario where baryon asymmetry generation is assisted by the kinetic motion of the Majoron, J, in the process of lepton-number violating inverse decays of a right-handed neutrino, N. We investigate two distinct scenarios depending on the sources of a Majoron kinetic motion: (1) the misalignment mechanism, and (2) the kinetic misalignment mechanism. The former case can naturally generate the observed baryon asymmetry for the Majoron mass mJ≳TeV and the right-handed neutrino’s mass MN≳1011 GeV. However, an additional decay channel of the Majoron is required to avoid the overclosure problem of the Majoron oscillation. The later scenario works successfully for mJ≲100 keV and MN≲109 GeV while MN can be even far below the temperature of the electroweak phase transition as long as sufficiently large kinetic misalignment is provided. We also find that a sub-100 keV Majoron is a viable candidate for dark matter. Published by the American Physical Society 2024