Muonium to antimuonium conversion and the decay micro+-->e+ nu -bare nu micro in left-right symmetric models.

We show that in the minimal left-right symmetric model with triplet Higgs bosons the range of the muon neutrino mass for which {nu}{sub {mu}} is required by cosmological considerations to be unstable can be probed by muonium to antimuonium conversion ({ital M}{r arrow}{ital {bar M}}) and/or by the exotic muon decay {mu}{sup +}{r arrow}{ital e}{sup +} {bar {nu}}{sub {ital e}}{nu}{sub {mu}}. We point out that if all the leptonic mixing matrices are hierarchical and the Dirac masses of the neutrinos are equal to the masses of the corresponding charged leptons, there is a lower bound in this range for the rates of both of these processes. We find {vert bar}{ital G}{sub {ital M}{ital {bar M}}}{vert bar}{approx gt}7{times}10{sup {minus}5}{ital G}{sub {ital F}} and {vert bar}{ital G}{sub {mu}}{sup ({ital e})}{vert bar}{approx gt}2{times}10{sup {minus}4}{ital G}{sub {ital F}} for the strength of the {ital M}{r arrow}{ital {bar M}} and {mu}{sup +}{r arrow}{ital e}{sup +} {bar {nu}}{sub {ital e}}{nu}{sub {mu}} interactions.