Baryogenesis from flavon decays

Mu-Chun Chen,Michael Ratz,Seyda Ipek

doi:10.1103/physrevd.100.035011

Mu-Chun Chen, Michael Ratz + Show 1 more

Open Access

https://doi.org/10.1103/physrevd.100.035011

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Abstract

Many popular attempts to explain the observed patterns of fermion masses involve a flavon field. Such weakly coupled scalar fields tend to dominate the energy density of the Universe before they decay. If the flavon decay happens close to the electroweak transition, the right-handed electrons stay out of equilibrium until the sphalerons shut off. We show that an asymmetry in the right-handed charged leptons produced in the decay of a flavon can explain the baryon asymmetry of the Universe.

Highlights

There is more matter than antimatter in the Universe
We show that the out-ofequilibrium decays of such a flavon can be the necessary beyond-the-Standard Model (SM) physics that generates the observed baryon asymmetry of the Universe (BAU)
We find that the observed baryon asymmetry is produced for 10−16 GeV ≲ ΓS ≲ 10−13 GeV. (2) The baryon asymmetry is virtually independent of the time tÃ when the flavon domination starts as long as TÃ ≫ Td, TEW. (3) As the flavon mass increases, its number density drops

Summary

INTRODUCTION

There is more matter than antimatter in the Universe. This baryon asymmetry of the Universe (BAU) is measured to be [1,2]. In order to produce the BAU, beyond-the-SM physics with additional degrees of freedom (d.o.f.) is needed. These d.o.f. can solve other deficiencies in the SM. These right-handed neutrinos are part of the seesaw mechanism [5], and provide an explanation for the smallness of neutrino masses Through their out-ofequilibrium decays, the observed BAU can be obtained. We show that the out-ofequilibrium decays of such a flavon can be the necessary beyond-the-SM physics that generates the observed BAU. In a universe where the flavon dominates the energy density, the right-handed electrons may not come into chemical equilibrium, and an asymmetry in these righthanded electrons can be converted into a baryon number asymmetry by sphalerons

BASIC MECHANISM

FLAVON ASYMMETRY

FLAVON COSMOLOGY

GENERATION AND NONEQUILIBRATION OF RIGHT-HANDED ELECTRONS

BARYON ASYMMETRY

CONCLUSIONS