New Limit on the Lepton-Flavor-Violating Decay ${\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\gamma}$

New Limit on the Lepton-Flavor-Violating Decay $μ^{+} \to e^{+} γ$

J. Adam et al. (MEG Collaboration)

Phys. Rev. Lett. 107, 171801 – Published 17 October 2011

Abstract

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay $μ^{+} \to e^{+} γ$ . The likelihood analysis of the combined data sample, which corresponds to a total of $1.8 \times 10^{14}$ muon decays, gives a 90% C.L. upper limit of $2.4 \times 10^{- 12}$ on the branching ratio of the $μ^{+} \to e^{+} γ$ decay, constituting the most stringent limit on the existence of this decay to date.