Experimental limits on massive neutrinos from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">−</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>annihilations at 29 GeV

A search was made in 29-GeV ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations for massive neutrinos decaying to ${e}^{\ifmmode\pm\else\textpm\fi{}}$${X}^{\ensuremath{\mp}}$(\ensuremath{\nu}) where X is a muon or meson. A 300-${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ data sample yielded just one candidate event with a mass ${m}_{\mathrm{eX}}$&gt;1.8 GeV. Significant limits are found for new neutrinos with masses from 1.8 to 6.7 GeV and with mixing parameters in the range 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$\ensuremath{\Vert}U${\ensuremath{\Vert}}^{2}$1. .AE