NEUTRINO RADIATIVE DECAY IN AN EXTERNAL ELECTROMAGNETIC-FIELD VIA VECTOR LEPTOQUARK

The massive neutrino radiative decay nu(i) --> nu(j) gamma (i not equa l j) is investigated within the Minimal Quark-Lepton Symmetry of the P ati-Salam type based on the SU(4)(V) x SU(2)(L) x G(R) group in an ext ernal constant crossed field (epsilon perpendicular to H, epsilon = H) . The matrix element Delta M((X)) and the decay probability W-(X) due to the leptoquark X contribution are analysed. The effect of significa nt enhancement of the neutrino decay by the crossed field takes place. It is shown that the leptoquark contribution to the decay probability can dominate over the W-boson one in the case of strong suppression o f the lepton mixing in the framework of the SM.