Proton decay and $\mu\to e+\gamma$ Connection in a Renormalizable SO(10) GUT for Neutrinos

TL;DR

This paper explores how different neutrino mass generation mechanisms in supersymmetric SO(10) GUT models affect predictions for proton decay and lepton flavor violating processes, providing testable differences between type I and II seesaw scenarios.

Contribution

It extends previous work by analyzing the type I seesaw case, showing it can accommodate large 3 mixing angles while suppressing proton decay, and identifies distinct experimental signatures for each scenario.

Findings

Type I seesaw can fit large 3 and suppress proton decay.

Type II seesaw also explains large 3 but with different flavor predictions.

Predicted observable 3 decay in  case, and observable 2 decay in type II case.

Abstract

Supersymmetric SO(10) grand unified models with renormalizable Yukawa couplings involving {\bf 10}, {\bf 126} and {\bf 120} Higgs fields have been shown to give a very economical theory for understanding quark-lepton flavor in a unified framework. In previous papers, we showed how nucleon decay can be suppressed in these models without invoking cancellation, by choice of Yukawa flavor texture within a type II seesaw framework for neutrinos that explains all mixings and masses including the recently observed "large" $\theta_{13}$. In this follow-up paper, we extend our earlier work to the case of type I seesaw and show that the recently measured "large" $\theta_{13}$ can be accommodated in this case while suppressing proton decay. We then point out that the two cases (type I and II) lead to different testable predictions for $B(\mu\to e+\gamma)$ and $B(\tau\to \mu (e) +\gamma)$ as well as different flavor final states in nucleon decay. In particular, we find that for the type I seesaw case, $B(\tau\to \mu +\gamma)$ can be observable while at the same time suppressing $B(\mu\to e+\gamma)$, whereas in the type II seesaw case, $B(\tau\to \mu +\gamma)$ is always suppressed whereas $B(\mu\to e+\gamma)$ is observable.