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Electroweak baryogenesis from late neutrino masses
Lawrence J Hall1, Hitoshi Murayama, Gilad Perez
1Theoretical Physics Group, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Physical Review Letters
|October 4, 2005
Summary
Electroweak baryogenesis requires a first-order phase transition. In the standard model, this fails due to hierarchical quark Yukawa matrices, but neutrino mass models offer a solution by generating baryon asymmetry via CP violation from neutrino Yukawa couplings.
Area of Science:
- Particle Physics
- Cosmology
- Beyond Standard Model Physics
Background:
- Standard Model electroweak baryogenesis fails due to hierarchical quark Yukawa matrices.
- Neutrino mass matrices are not hierarchical, suggesting alternative baryogenesis mechanisms.
- Existing models struggle to explain the observed baryon asymmetry of the universe.
Purpose of the Study:
- To investigate if low-scale neutrino mass generation can explain the observed baryon asymmetry.
- To explore the role of neutrino Yukawa couplings in electroweak baryogenesis.
- To identify potential observable consequences of such a mechanism.
Main Methods:
- Analyzing CP violation in heavy lepton reflection by the Higgs bubble wall.
- Incorporating neutrino mass generation at low energy scales.
- Exploring models with non-hierarchical neutrino mass matrices.
Main Results:
- Neutrino Yukawa couplings can induce significant CP violation in heavy lepton reflection.
- This CP violation can generate the observed baryon asymmetry of the universe.
- The mechanism predicts new vectorlike leptons below the TeV scale.
Conclusions:
- Low-scale neutrino mass generation provides a viable mechanism for electroweak baryogenesis.
- This mechanism circumvents the limitations of the Standard Model.
- Observable signatures include new vectorlike leptons and potential mu --> e transitions.