Study of muon-number-violating hyperon decays

Muon-number-violating hyperon decays are discussed, first from a phenomenological point of view and then considering some possible sources of muon-number violation. We show that branching ratios as large as of the order of ${10}^{-6\mathrm{}}$ for the decays ${\Sigma }^{+}\to p{\mu }^{\mp }{e}^{\pm }$ and ${\Xi }^0\to \Lambda {\mu }^{\mp }{e}^{\pm }$ cannot be ruled out. We note, however, that such branching ratios are unlikely, since they would require muon-number-violating interactions of very special structure.