The Dark Side of $\theta_{13}$, $\delta_{CP}$, Leptogenesis and Inflation in Type-I Seesaw

TL;DR

This paper presents a framework within the type-I seesaw mechanism that simultaneously explains nonzero $ heta_{13}$, leptogenesis, dark matter, and inflation, aligning with recent experimental results.

Contribution

It introduces a model where additional particles break residual flavor symmetry, enabling nonzero $ heta_{13}$, leptogenesis, dark matter, and inflation in a unified setup.

Findings

Achieves nonzero $ heta_{13}$ and $ heta_{CP}$ consistent with experiments.

Provides a dark matter candidate from $Z_2$ odd particles.

Models inflation with a scalar matching BICEP2 results.

Abstract

In the context of the type-I seesaw mechanism, it is known that $\theta_{13}$ is zero and leptogenesis can not be realized if there exists a residual flavor symmetry resulting in the Tri-Bimaximal neutrino mixing pattern. We propose a simple framework where additional particles, odd under a $Z_2$ symmetry, break the residual flavor symmetry and the lightest of the $Z_2$ odd particles is the dark matter candidate. As as result, nonzero $\theta_{13}$, $\delta_{CP}$, leptogenesis and the correct dark matter density can be accommodated. On the other hand, a $Z_2$ odd scalar can play the role of the inflaton with mass of $10^{13}$ GeV motivated by the recent BICEP2 results. Interestingly, the model can "generate" $\delta_{CP} \simeq -\pi/2$, preferred by the T2K experiment in the normal hierarchy neutrino mass spectrum.