Improved search for two body muon decay ⁺ e⁺ X_H

Charged lepton flavor violating muon decay mu(+) -> e(+) X-H, where X-H is a massive neutral boson, was sought by searching for extra peaks in the muon decay mu(+) -> e(+)nu(nu) over bar energy spectrum in the m(XH), mass region 47.8-95.1 MeV/c(2). No signal was found and 90% confidence level upper limits were set on the branching ratio Gamma(mu(+) -> e(+) X-H)/Gamma(mu(+)-> e(+)nu(nu) over bar) at the level of 10(-5) for this region.