Search for heavy-neutrino production ine+e−annihilation at 29 GeV

We report a search for long-lived heavy neutrinos produced by the neutral weak current in e+e- annihilation at 29 GeV at the SLAC storage ring PEP. Data from the Mark II detector are examined for evidence of events with one or more separated vertices in the radial range of 2 mm to 10 cm. No events were found that were consistent with the search hypothesis, ruling out heavy neutrinos with mean decay lengths of 1 to 20 cm in the mass range 1 to 13 GeV/c2. © 1987 The American Physical Society.