arXiv subjects

Nobuchika Okada

Publications and source records attributed to Nobuchika Okada.

293 records · Page 17Linked to original sources

arXiv1997

A Supersymmetric Composite Model with Dynamical Supersymmetry Breaking

We present a supersymmetric composite model with dynamical supersymmetry breaking. The model is based on the gauge group $SU(2)_S \times SU(2)_H \times SU(3)_c \times SU(2)_L \times U(1)_Y$. Supersymmetry is dynamically broken by the non-perturbative effect of the $SU(2)_S$ `supercolor' interaction. The large top Yukawa coupling is naturally generated by the $SU(2)_H$ `hypercolor' interaction as recently proposed by Nelson and Strassler. The supersymmetry breaking is mediated to the standard model sector by a new mechanism. The electroweak symmetry breaking is caused by the radiative correction due to the large top Yukawa coupling with the supersymmetry breaking. This is the `radiative breaking scenario', which originates from the dynamics of the supercolor and hypercolor gauge interactions.

hep-ph↗

arXiv1996

A sterile neutrino scenario constrained by experiments and cosmology

We discuss a model in which three active and one sterile neutrino account for the solar, the atmospheric and the LSND neutrino anomalies. It is shown that if $N_ν<4$ then these and other experiments and big bang nucleosynthesis constrain all the mixing angles severely, and allow only the small-angle MSW solution. If these neutrinos are of Majorana type, then negative results of neutrinoless double beta decay experiments imply that the total mass of neutrinos is not sufficient to account for all the hot dark matter components.

hep-ph↗

arXiv1996

Neutrino Flavor Mixing in the `Doublet-Singlet Oscillation' Model

Recently, it was pointed out that the solar and atmospheric neutrino deficits can be explained by oscillations between electroweak doublet and singlet neutrinos in the model of Majorana neutrinos. However, since the model includes no flavor mixing, it cannot explain the recent LSND result. We extend the model to include the flavor mixing, and obtain the explanation of the LSND result together with the solar and atmospheric neutrino deficits. The requirement for the neutrinos to be the hot dark matter selects out only the vacuum oscillation solution to the solar neutrino deficit.

hep-ph↗

arXiv1996

Doublet-Singlet Oscillations and Dark Matter Neutrinos

We examine the `singlet majoron model' first introduced by Chikashige, Mohapatra and Peccei as a simple extension of the standard model with massive Majorana neutrinos. We can explain both the solar and the atmospheric neutrino deficits by the oscillations between electroweak doublet and singlet neutrinos without flavor mixing. Furthermore, while some light neutrinos can be the hot dark matter, tau neutrino with mass of 8.9-24 MeV can be the cold dark matter through the interaction with the majoron. Thus, we can simultaneously explain the solar neutrino deficit, the atmospheric neutrino anomaly, and the cold and hot dark matters only with the Majorana neutrinos.

hep-ph↗

arXiv1996

Majorana Neutrinos as the Dark Matters in the Cold plus Hot Dark Matter Model

A simple model of the Majorana neutrino with the see-saw mechanism is studied, assuming that two light neutrinos are the hot dark matters with equal mass of 2.4 eV in the cold plus hot dark matter model of cosmology. We find that the heavy neutrino, which is the see-saw partner with the remaining one light neutrino, can be the cold dark matter, if the light neutrino is exactly massless. This cold dark matter neutrino is allowed to have the mass of the wide range from 5.9 x 10^2 eV to 2.2 x 10^7 eV.

hep-ph↗