¹ BRITTON 1992B is from a search for additional peaks in the ${{\mathit e}^{+}}$ spectrum from ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ decay at TRIUMF. See also BRITTON 1992 .

² BRYMAN 1983B obtain upper limits from both direct peak search and analysis of B( ${{\mathit \pi}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}$ )$/$B( ${{\mathit \pi}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \nu}}$ ). Latter limits are not listed, except for this entry (i.e. $-$ we list the most stringent limits for given mass).

³ Analysis of ( ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ )$/$( ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{\mu}}}$ ) and ( ${{\mathit K}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ )$/$( ${{\mathit K}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{\mu}}}$ ) decay ratios.

⁴ Analysis of ( ${{\mathit K}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ ) spectrum.

References:

BRITTON

1992B

PR D46 885

Improved Search for Massive Neutrinos in ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}}$ Decay

DELEENER-ROSIER

1991

PR D43 3611

Search for Massive Neutrinos in ${{\mathit \pi}}$ $\rightarrow$ ${{\mathit e}^{-}}{{\mathit \nu}}$ Decay

AZUELOS

1986

PRL 56 2241

Constraints on Massive Neutrinos in ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ Decay

BRYMAN

1983B

PRL 50 1546

Search for Massive Neutrinos in ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ Decays

SHROCK

1981

PR D24 1232

General Theory of Weak Processes Involving Neutrinos. 1. Leptonic Pseudoscalar Meson Decays, with Associated Tests for, and Bounds on, Neutrino Masses and Lepton Mixing

SHROCK

1980

PL 96B 159

New Tests for, and Bounds on, Neutrino Masses and Lepton Mixing

BRITTON

1992

PRL 68 3000

Measurement of the ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}}$ Branching Ratio