MUON DECAYS WITH LEPTON-NUMBER VIOLATION VIA VECTOR LEPTOQUARK

The decays mu --> ey, mu --> eyy, and mu --> ee ($) over bar e are ana lysed in the framework of the Pati-Salam type quark-lepton symmetry SU (4)(V)xSU(2)(L)xG(R) where the effects of mixing in the quark-lepton c urrents are taken into account. It is shown that the mu --> eyy and mu --> ee ($) over bar e decays via the vector leptoquark have not a GIM -type suppression, while the mu --> ey decay has. So, the specific hie rarchy of the decay probabilities could take place Gamma(mu --> ee ($) over bar e) >> Gamma(mu --> eyy) >> Gamma(mu --> ey). The existing bo unds on the vector leptoquark mass and on the mixing matrix elements, based on the data for the mu e conversion in nuclei and for the ratio of the K-e2 and K-p2 decays allow to set the upper limits on the branc hing ratios at a level of 10(-18) for the mu --> eyy decay and at a le vel of 10(-15) for the mu --> ee ($) over bar e decay.