arXiv subjects

N. Shimoyama

Publications and source records attributed to N. Shimoyama.

4 recordsLinked to original sources

arXiv2002

Lepton Flavor Violating Processes in Bi-maximal Texture of Neutrino Mixings

We investigate the lepton flavor violation in the framework of the MSSM with right-handed neutrinos taking the large mixing angle MSW solution in the quasi-degenerate and the inverse-hierarchical neutrino masses. We predict the branching ratio of $μ\to e+γ$ processes assuming the degenerate right-handed Majorana neutrino masses. We find that the branching ratio in the quasi-degenerate neutrino mass spectrum is 100 times smaller than the ones in the inverse-hierarchical and the hierarchical neutrino spectra. We emphasize that the magnitude of $U_{e3}$ is one of important ingredients to predict BR($μ\to e +γ$). The effect of the deviation from the complete-degenerate right-handed Majorana neutrino masses are also estimated.

hep-ph↗

arXiv2002

See-Saw Realization of the Texture Zeros in the Neutrino Mass Matrix

We study the see-saw realization of seven textures of the neutrino mass matrix, which were presented by Frampton, Glashow and Marfatia. Two of them B_1 and B_2 are not realized in the see-saw mechanism without fine-tuning of parameters. We present some specific textures of the Dirac neutrino mass matrix and the right-handed Majorana neutrino one. In order to test these textures, we discuss the effect on the branching ratio of mu --> e gamma. We also study the U(1)_X times U(1)_{X'} flavor symmetry, in which U(1)_X is anomalous and U(1)_{X'} is non-anomolous, to reproduce texture zeros. We present examples of U(1) charges for two textures A_1 and A_2$.

hep-ph↗

arXiv2002

Lepton Flavor Violating Process in Bi-maximal texture of Neutrino Mixings

We investigate the lepton flavor violation in the framework of the MSSM with right-handed neutrinos taking the large mixing angle MSW solution in the quasi-degenerate and the inverse-hierarchical neutrino masses. We predict the branching ratio of $μ\to e+γ$ and $τ\to μ+γ$ processes assuming the degenerate right-handed Majorana neutrino masses. We find that the branching ratio in the quasi-degenerate neutrino mass spectrum is 100 times smaller than the ones in the inverse-hierarchical and the hierarchical neutrino spectra. We emphasize that the magnitude of $U_{e3}$ is one of important ingredients to predict BR($μ\to e +γ$). The effect of the deviation from the complete-degenerate right-handed Majorana neutrino masses are also estimated. Furtheremore, we examine the $S_{3\sL}\times S_{3\sR}$ model, which gives the quasi-degenerate neutrino masses, and the Shafi-Tavartkiladze model, which gives the inverse-hierarchical neutrino masses. Both predicted branching ratios of $μ\to e+γ$ are smaller than the experimantal bound.

hep-ph↗

arXiv2001

Lepton Flavor Violating Process in Degenerate and Inverse-Hierarchical Neutrino Models

We have investigated the lepton flavor violation in the supersymmetric framework assuming the large mixing angle MSW solution with the quasi-degenerate and the inverse-hierarchical neutrino masses. In the case of the quasi-degenerate neutrinos, the predicted branching ratio BR$(μ\to e γ)$ strongly depends on $m_ν$ and $U_{e3}$. For $U_{e3}\simeq 0.05$ with $m_ν\simeq 0.3 \eV$, the prediction is close to the present experimental upper bound if the right-handed Majorana neutrino masses are degenerate. On the other hand, the prediction is larger than the experimental upper bound for $U_{e3}\geq 0.05$ in the case of the inverse-hierarchical neutrino masses.

hep-ph↗