Leptogenesis driven by majoron

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 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 $m_J\gtrsim \mathrm{T}\mathrm{e}\mathrm{V}$ and the right-handed neutrino’s mass $M_N\gtrsim {10}^{11}\mathrm{G}\mathrm{e}\mathrm{V}$. 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 $m_J\lesssim 100\mathrm{k}\mathrm{e}\mathrm{V}$, and $M_N\lesssim {10}^9\mathrm{G}\mathrm{e}\mathrm{V}$ while $M_N$ 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-$100\mathrm{k}\mathrm{e}\mathrm{V}$ majoron is a viable candidate for dark matter.