Search for heavy neutrinos in π → μν decay

A. Aguilar-Arevalo, M. Aoki, M. Blecher, D.I. Britton, D. vom Bruch, D.A. Bryman, S. Chen, J. Comfort, L. Doria, S. Cuen-Rochin, P. Gumplinger, A. Hussein (+12 others)
2019 Physics Letters B  
In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays π + → μ + ν at rest by examining the observed muon energy spectrum for extra peaks in addition to the expected peak for a light neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix |U μi | 2 in the neutrino mass region of 15.7-33.8 MeV/c 2 , improving on previous results by an order of magnitude.
doi:10.1016/j.physletb.2019.134980 fatcat:efcsbo6kirbxrl4vl6ldlei3q4