Spontaneous CP Violation in next to minimal renormalizable SUSY SO(10)

TL;DR

This paper demonstrates that in the next-to-minimal SUSY SO(10) model, spontaneous CP violation naturally occurs due to complex singlet VEVs, leading to lower scalar potential minima and realistic fermion mass fits.

Contribution

It provides a detailed analysis showing that complex MSSM singlet VEVs induce spontaneous CP violation with the lowest potential minimum, confirming the phenomenon in this model.

Findings

Complex MSSM singlet VEVs lead to lower minima than real ones.

Spontaneous CP violation is naturally realized in the model.

Realistic fermion mass and mixing fits are achievable.

Abstract

The minimal renormalizable SUSY SO(10) model is a very compact and predictive theory. It was very popular till one realized that it cannot account for the masses of the neutrinos. The best cure to this problem is to add the 120 Higgs representaion, the 'next to minimal' version. To reduce the number of free parameters, it was suggested in recent papers to use only real parameters in the superpotential and induce CP violation via complex VEVs. This is what one usually calls 'spontaneous CP violation'. The number of free parameters turned out, then, to be even smaller than in the original minimal model and good fits to all known masses and mixings were obtained. Out of those papers only that of Aulakh and Garg discusses how CP is spontaneously violated. Some heavy MSSM singlet VEVs generate a phase at high scale and CP violationis carried down to the CKM matrix by the mixing of the scalar MSSM doublets. They study the model in great detail and give a large set of solutions. As a proof of principle, two of the solutions are shown to induce realistic phenomenological fits. It is not clear, however, how the right physical solution is obtained. I study the way solutions for spontaneous CP violation affect the scalar potential. The one that gives the lowest minimum of the potential, in terms of a given set of parameters, is the right physical one. In the way of doing so, I will prove that complex MSSM singlet VEVs lead actually to lower minima than the real (CP conserving) ones. This proves that CP is spontaneously violated in this model.