VECTOR LEPTOQUARKS COULD BE RATHER LIGHT

Some low-energy manifestations of a minimal extension of the Standard Model based on the quark-lepton SU(4)v x SU(2)L x G(R) symmetry of the Pati-Salam type are analysed. Given this symmetry a new type of mixin g in the quark-lepton interactions is shown to be required. An additio nal arbitrariness of the mixing parameters could allow to decrease not iceably the lower bound on the leptoquark mass M(X) originated from th e pi and K decays and the mue conversion. The only mixing independent bound emerging from the cosmological limit on the pi0 --> nunuBAR deca y width is M(X) > 18 TeV.