Leptogenesis without on-shell right-handed neutrinos

@misc{clery2026leptogenesis,
  title = {{Leptogenesis without on-shell right-handed neutrinos}},
  author = {Simon Cléry and Alejandro Ibarra and Onur Yonar},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2605.24163},
  eprint = {2605.24163},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2605.24163},
}

TY  - UNPB
TI  - Leptogenesis without on-shell right-handed neutrinos
AU  - Simon Cléry
AU  - Alejandro Ibarra
AU  - Onur Yonar
PY  - 2026
DA  - 2026/10/05
PB  - arXiv
DO  - 10.48550/arxiv.2605.24163
UR  - https://arxiv.org/abs/2605.24163
AB  - We propose a novel mechanism for generating the baryon asymmetry of the Universe through leptogenesis in a scenario where the right-handed neutrinos are heavier than the maximal temperature of the Universe, and are never produced on-shell, neither by thermal nor by non-thermal mechanisms. We introduce a new scalar field, ϕ, lighter than the right-handed neutrinos, that couples to the latter via a Yukawa coupling, so that it decays into two lepton doublets and two higgs doublets via off-shell right-handed neutrinos. Then, we derive the CP asymmetry arising from the interference between tree-level and loop diagrams in the four-body decay, and we show that the generated baryon asymmetry can reproduce the observed value both in a scenario where ϕ is responsible for the reheating of the Universe, and in a scenario where ϕ is a generic scalar that remains in thermal equilibrium with the plasma.
ER  -