Fermion texture and sterile neutrinos

An explicit form of charged-lepton mass matrix, predicting m tau = 1776.80 MeV from the experimental values of m(e) and m(mu) (in good agreement with the experimental figure m(tau) = 1777.05(-0.26)(+0.29) MeV), is applied to three neutrinos nu(e), nu(mu), nu(tau) in order to correlate tentatively th eir masses and mixing parameters. It is suggested that for neutrinos the di agonal elements of the mass matrix are small versus its off-diagonal elemen ts. Under such a conjecture, the neutrino masses, lepton Cabibibo-Kobayashi -Maskawa matrix and neutrino oscillation probabilities are calculated in th e corresponding lowest perturbative order. Then, the nearly maximal mixing of nu(mu) and nu(tau) is predicted in consistency with the observed deficit of atmospheric nu(mu)'s. However, the predicted deficit of solar nu(e)'s i s much too small to explain the observed effect, what suggests the existenc e of (at least) one sort, nu(s)((e)) of sterile neutrinos, whose mixing wit h nu(e) would be responsible for the observed deficit. Perspectives Tar app lying the same form of mass matrix to quarks are also outlined. Two indepen dent predictions of \V-ub\/\V-cb\ = 0.0753 +/- 0.0032 and unitary angle gam ma similar or equal to 70 degrees are deduced from the experimental values of IV,,I and \V-cb\ (With the use of quark masses m(s), m(c) and m(b)). In the last three Sections, the option of two sorts, nu(s)((e)) and nu(s)((mu) ), of sterile neutrinos is considered. They may dominate neutrino mixing, a nd even cause that two extra neutrino mass states (arising then) are agents of some tiny neutrino instability and related damping of nu(e) and nu(mu) oscillations. In Appendix, three conventional Majorana sterile neutrinos ar e discussed.