Abstract
In superstring models with E6 singlets coming from H1(End T), in addition to the couplings 27×27×27 and 27×27×27, there are the couplings 27×27×1 and 27×27×1. It is shown in this paper that the general mass matrix of neutrinos is [5(p1+p2)+p3]×[5(p1+p2)+p3], where p1, p2, and p3 are the numbers of 27, 27, and the singlets of E6, respectively. By appropriate choice of vacuum expectation values and letting p1=p1=p3=1, the 11×11 mass matrix reduces to 4×4, from which a light neutrino with mass m<10 eV is obtained. © 1987 The American Physical Society.