A search for two body muon decay signals

Lepton family number violation is tested by searching for mu(+) -> e(+)X(0) decays among the 5.8 x 10(8) positive muon decay events analyzed by the TWIST collaboration. Limits are set on the production of both massless and massive X-0 bosons. The large angular acceptance of this experiment allows limits to be placed on anisotropic mu(+) -> e(+)X(0) decays, which can arise from interactions violating both lepton flavor and parity conservation. Branching ratio limits of order 10(-5) are obtained for bosons with masses of 13-80 MeV/c(2) and with different decay asymmetries. For bosons with masses less than 13 MeV/c(2) the asymmetry dependence is much stronger and the 90% limit on the branching ratio varies up to 5.8 x 10(-5). This is the first study that explicitly evaluates the limits for anisotropic two body muon decays.