Neutrino Mixing in a Democratic-Seesaw-Mass-Matrix Model

Abstract

On the basis of a seesaw-type mass matrix model for quarks and leptons, $M_f\simeq m_L{M}_F^{-1}{m}_R$, where $m_L\propto m_R$ are universal for $f=u,d,\nu$ and $e$ (up-quark-, down-quark-, neutrino- and charged lepton-sectors), and $M_F$ has a form [(unit matrix)+(democratic-type matrix)], neutrino masses and mixings are investigated. It is tried to understand a large ${\nu }_{\mu }$-${\nu }_{\tau }$ mixing, i.e., ${\sin }^{2}2{\theta }_{23}\sim 1$, with $m_{\nu 1}\ll m_{\nu 2}\sim m_{\nu 3}$, which has been suggested by the atmospheric neutrino data.

Comments: 11 pages (latex) + 3 figures (postscript), uuencoded