The Dark Side of ${\theta }_{13}$, ${\delta }_{CP}$, Leptogenesis and Inflation in Type-I Seesaw

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.

Comments: 23 pages, 8 Figures and 5 Tables. v3: a toy A4 flavor model provided, version accepted by JHEP