Axion in the minimal SO(10) GUT

Abstract

The QCD axion is investigated within the minimal supersymmetric SO(10) grand unified theory, where the Yukawa sector involves Higgs multiplets $10$ and $\overline{126}$. The relative phase between the VEVs of $(10,1,3)\subset \overline{126}$ and $(\overline{10},1,3)\subset 126$ under $\mathrm{SU}(4{)}_C\times \mathrm{SU}(2{)}_L\times \mathrm{SU}(2{)}_R$ is identified with the axion. The Peccei-Quinn and $B-L$ symmetry breaking scales coincide through $|⟨{\Delta }_R⟩|=|⟨{\overline{\Delta }}_R⟩|$. The scalar partner of the lightest right-handed neutrino plays the role of the inflaton, realizing hybrid inflation consistent with the observed CMB density fluctuations. After inflation, both fields acquire VEVs, and the domain-wall problem is resolved through the Lazarides-Shafi mechanism, which naturally restricts the model to three generations.

Comments: 11 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:hep-ph/0412373