Charged lepton flavor violating muon decay ${ \mu}^+{ \rightarrow}e^+X_H$, where $X_H$ is a massive neutral boson, was sought by searching for extra peaks in the muon decay ${ \mu}^+{ \rightarrow}e^+{ \nu}\bar{ \nu}$ energy spectrum in the $m_{ X_H}$ 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 ${ \Gamma}({ \mu}^+{ \rightarrow}e^+X_H)/{ \Gamma}({ \mu}^+{ \rightarrow}e^+{ \nu}\bar{ \nu})$ at the level of $10^{ -5}$ for this region.
Categories: hep-ex nucl-ex