Abstract
Although SO(10) Supersymmetric (SUSY) Grand Unification Theories (GUTs) are very attractive for neutrino mass and mixing, it is often quite difficult to achieve successful leptogenesis from the lightest right-handed neutrino N1 due to the strong relations between neutrino and up-type quark Yukawa couplings. We show that in a realistic model these constraints are relaxed, making N1 leptogenesis viable. To illustrate this, we calculate the baryon asymmetry of the Universe YB from flavoured N1 leptogenesis in a recently proposed Δ(27) × SO(10) SUSY GUT. The flavoured Boltzmann equations are solved numerically, and comparison with the observed YB places constraints on the allowed values of right-handed neutrino masses and neutrino Yukawa couplings. The flavoured SO(10) SUSY GUT is not only fairly complete and predictive in the lepton sector, but can also explain the BAU through leptogenesis with natural values in the lepton sector albeit with some tuning in the quark sector.
Highlights
The Standard Model (SM), while otherwise phenomenologically successful, fails to explain the observed baryon asymmetry of the Universe (BAU), i.e. the presence of more matter than antimatter
In this paper we have shown that a realistic model relaxes these constraints, making N1 leptogenesis viable
To illustrate this we have calculated the baryon asymmetry of the Universe YB from flavoured N1 leptogenesis in a recently proposed ∆(27) × SO(10) SUSY Grand Unification Theories (GUTs) of Flavour
Summary
The Standard Model (SM), while otherwise phenomenologically successful, fails to explain the observed baryon asymmetry of the Universe (BAU), i.e. the presence of more matter than antimatter. We estimate the BAU arising from leptogenesis in a ∆(27) × SO(10) SUSY GUT model [14], which was shown to successfully and accurately fit all quark and lepton mass and mixing parameters, while simultaneously resolving the doublet-triplet splitting problem and demonstrating that proton decay is naturally suppressed well within the current experimental constraints It further predicts normal neutrino ordering, and a leptonic Dirac phase δCP ≈ −π/2, in good agreement with current experimental bounds. A compelling feature of the model is that the mass matrices in each sector (including the light neutrinos after the seesaw has been implemented) have the same universal structure, and the phases and mixing angles in the leptonic sector are guided by the flavour symmetry This leads to a rather predictive scenario for leptogenesis, which allows to constrain some of the free parameters of the model (and indirectly, the mass of the RH neutrinos) in order to obtain the correct asymmetry. Appendix C derives a useful result for the seesaw mechanism with rank-one matrices
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