0000000000306411
AUTHOR
Ernest Ma
Radiative Seesaw Dark Matter
The singlet majoron model of seesaw neutrino mass is appended by one dark Majorana fermion singlet $\chi$ with $L=2$ and one dark complex scalar singlet $\zeta$ with $L=1$. This simple setup allows $\chi$ to obtain a small radiative mass anchored by the same heavy right-handed neutrinos, whereas the one-loop decay of the standard-model Higgs boson to $\chi \chi + \bar{\chi} \bar{\chi}$ provides the freeze-in mechanism for $\chi$ to be the light dark matter of the Universe.
Minimal supergravity radiative effects on the tri-bimaximal neutrino mixing pattern
7 pages, 3 figures.-- PACS nrs.: 14.60.Pq, 12.60.Jv.-- ISI Article Identifier: 000245333000012.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0606082
Predicting Neutrinoless Double Beta Decay
We give predictions for the neutrinoless double beta decay rate in a simple variant of the A_4 family symmetry model. We show that there is a lower bound for the neutrinoless double beta decay amplitude even in the case of normal hierarchical neutrino masses, corresponding to an effective mass parameter |m_{ee}| >= 0.17 \sqrt{\Delta m^2_{ATM}}. This result holds both for the CP conserving and CP violating cases. In the latter case we show explicitly that the lower bound on |m_{ee}| is sensitive to the value of the Majorana phase. We conclude therefore that in our scheme, neutrinoless double beta decay may be accessible to the next generation of high sensitivity experiments.
Underlying A_4 Symmetry for the Neutrino Mass Matrix and the Quark Mixing Matrix
The discrete non-Abelian symmetry $A_4$, valid at some high-energy scale, naturally leads to degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino mass splittings and mixing angles (one of which is necessarily maximal and the other large) are then induced radiatively in the context of softly broken supersymmetry. The quark mixing matrix is also calculable in a similar way. The mixing parameter $U_{e3}$ is predicted to be imaginary, leading to maximal CP violation in neutrino oscillations. Neutrinoless double beta decay and $\tau \to \mu \gamma$ should be in the experimentally accessible range.