Search for the rare decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\nu}$

Search for the rare decay $K^{+} \to μ^{+} ν \bar{ν} ν$

A. V. Artamonov et al. (E949 Collaboration)

Phys. Rev. D 94, 032012 – Published 31 August 2016

Abstract

Evidence of the $K^{+} \to μ^{+} ν \bar{ν} ν$ decay was searched for using E949 (Brookhaven National Laboratory, USA) experimental data with an exposure of $1.70 \times 1 0^{12}$ stopped kaons. The data sample is dominated by the background process $K^{+} \to μ^{+} ν_{μ} γ$ . An upper limit on the decay rate $Γ (K^{+} \to μ^{+} ν \bar{ν} ν) < 2.4 \times 10^{- 6} Γ (K^{+} \to all)$ at 90% confidence level was set assuming the standard model muon spectrum. The data are presented in such a way as to allow calculation of rates for any assumed $μ^{+}$ spectrum.