Lopsided Mass Matrices Research Articles

Erratum: Bounds on the neutrino mixing angles andCPphase for anSO(10)model with lopsided mass matrices [Phys. Rev. D72, 013001 (2005)

The bounds on the neutrino mixing angles and CP Dirac phase for an SO(10) model with lopsided mass matrices, arising from the presence of ${\bf 16}_H$ and $\bar{\bf 16}_H$ Higgs representations, are studied by variation of the one real and three unknown complex input parameters for the right-handed Majorana neutrino mass matrix. The scatter plots obtained favor nearly maximal atmospheric neutrino mixing, while the reactor neutrino mixing lies in the range $10^{-5} \lsim \sin^2 \theta_{13} \lsim 1 \times 10^{-2}$ with values greater than $10^{-3}$ most densely populated. A rather compelling scenario within the model follows, if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal. We then find the scatter plots are reduced to narrow bands, as the mixing angles and CP phase become highly correlated and predictive. The bounds on the mixing angles and phase then become $0.45 \lsim \sin^2 \theta_{23} \lsim 0.55$, $0.38 \lsim \tan^2 \theta_{12} \lsim 0.50$, $0.002 \lsim \sin^2 \theta_{13} \lsim 0.003$, and $60^\circ \lsim \pm \delta_{CP} \lsim 85^\circ$. Moreover, successful leptogenesis and subsequent baryogenesis are also obtained, with $\eta_B$ increasing from $(2.7 to 6.3) \times 10^{-10}$ as $\sin^2 \theta_{23}$ increases from 0.45 to 0.55.

Bounds on the neutrino mixing angles andCPphase for anSO(10)model with lopsided mass matrices

The bounds on the neutrino mixing angles and CP Dirac phase for an SO(10) model with lopsided mass matrices, arising from the presence of ${\bf 16}_H$ and $\bar{\bf 16}_H$ Higgs representations, are studied by variation of the one real and three unknown complex input parameters for the right-handed Majorana neutrino mass matrix. The scatter plots obtained favor nearly maximal atmospheric neutrino mixing, while the reactor neutrino mixing lies in the range $10^{-5} \lsim \sin^2 \theta_{13} \lsim 1 \times 10^{-2}$ with values greater than $10^{-3}$ most densely populated. A rather compelling scenario within the model follows, if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal. We then find the scatter plots are reduced to narrow bands, as the mixing angles and CP phase become highly correlated and predictive. The bounds on the mixing angles and phase then become $0.45 \lsim \sin^2 \theta_{23} \lsim 0.55$, $0.38 \lsim \tan^2 \theta_{12} \lsim 0.50$, $0.002 \lsim \sin^2 \theta_{13} \lsim 0.003$, and $60^\circ \lsim \pm \delta_{CP} \lsim 85^\circ$. Moreover, successful leptogenesis and subsequent baryogenesis are also obtained, with $\eta_B$ increasing from $(2.7 to 6.3) \times 10^{-10}$ as $\sin^2 \theta_{23}$ increases from 0.45 to 0.55.

Lopsided mass matrices and leptogenesis in SO(10) GUT

Lopsided structure in mass matrices of down quarks and leptons gives a simple explanation for the observed large angles of neutrino mixings. We realize such mass matrices by the Froggatt–Nielsen mechanism in the framework of supersymmetric SO(10) grand unified theory (GUT). It is shown that the model can reproduce the successful mass matrices which have been obtained in SU(5) models. Cosmological implication of the model is also discussed. We show that the hybrid inflation occurs naturally in the model and it offers non-thermal leptogenesis by decays of the next-to-lightest right-handed neutrinos. The present baryon asymmetry is explained by just the oscillation mass scale in the atmospheric neutrinos.

Bimaximal neutrino mixings from lopsided mass matrices

Current solar and atmospheric neutrino oscillation data seem to favor a bimaximal pattern for neutrino mixings where the matrix elements U_{e2} and U_{\mu 3} are of order one, while U_{e3} is much smaller. We show that such a pattern can be obtained quite easily in theories with ``lopsided'' mass matrices for the charged leptons and the down type quarks. A relation connecting the solar and atmospheric neutrino mixing angles is derived, \tan^2\theta_{atm} \simeq 1+ \tan^2\theta_{sol}, which predicts \sin^2 2\theta_{atm} \simeq 0.97 corresponding to the best fit LMA solution for solar neutrinos. Predictive schemes in SO(10) realizing these ideas are presented. A new class of SO(10) models with lopsided mass matrices is found which makes use of an adjoint VEV along the I_{3R} direction, rather than the traditional B-L direction.