The Neutrino Masses in Susy Gut

The neutrino mass problem in SU(4) × SU(2)L × SU(2)R SUSY GUT obtained from the compactification of E8 × E8 heterotic string is analyzed. The estimated values of the neutrino masses and mixing angles can explain the experimental data on solar neutrino flux. Yerevan Physics Institute Yerevan 1995 Recent solar neutrino experiments give an evidence for nonzero neutrino masses. The solar neutrino deficit can be explained in terms of the neutrino resonant oscillations if the neutrino mass difference is of order: ∆m ∼ (0.3− 1.2) ·10−5eV 2 or vacuum oscillations if ∆m ∼ (0.5−1.1) ·10−10eV 2 [1, 2, 3]. It is well-known, that in SO(10) GUT small neutrino masses can be obtained via seesaw mechanism [4]. The neutrino mass matrix for three left νe, νμ, ντ and three right ν c e , ν c μ, ν c τ neutrinos has the following form: